How do I verify the validity of a Foursquare Checkin? - foursquare

Using the Foursquare API, is there any way to determine how distant a user was from the venue he checked in at? The checkin object returned doesn't have any indication what the user GPS coordinates were.

Foursquare purposefully does not expose a "cheat" bit or the user's device reported distance from a venue via the API. The vast vast majority of users of foursquare do not cheat and the majority of "irregularities" between a user's reported location and the venue's location are due to poor GPS accuracy or are because the user is making a "post-check-in" at a location they were at but forgot to check into earlier.
My advice for developers re: cheating is to either ignore it and/or detect it after-the-fact.
Ignore cheats: The cost/benefit ratio of trying to detect cheating is generally not worth it. Not only is it effort to build an effective system, but you will you frequently have false positives where you penalize legitimate usage, causing you to disenfranchise users trying to use the system as intended, through no fault of their own. If you remain worried, then you can design your system such that the user either gains little by cheating (they're only depriving themselves, or the reward is physical so they gain nothing) or will have social pressures against cheating (e.g. foursquare's friend-scoped leaderboard means that it's generally clear to friends if a user is blatantly cheating, nullifying any real benefit to the cheating user)
Detect cheats after the fact: You'll have better luck/precision detecting cheating post-fact when you can look at the whole of a user's activity, rather than trying to make a decision with each check-in. A use who cheats often should be fairly easy to detect with a periodic job using simple rules. A user that cheats once out of 100 check-ins will be harder to detect, but that's going to be true no matter what mechanisms you chose to adopt (and you're better off with an occasional false negative than an occasional false positive)

Perhaps.
From the API docs for the Checkin response object:
Checkin Response
location Optional If the type of this checkin is "shout" or "venueless", this field may be present and may contains a lat, lng pair and/or a name, providing unstructured information about the user's current location.

I think that cannot be done for a normal checkin with the current API. ll (latitude and longitude) is even not a required field for a checkin in the current API version.

Related

Online test security measures

I'm developing a feature for a client in which users voluntarily take an important test online. The test is difficult and the users will be highly motivated to do well (think SATs or GRE, etc)... so there's also a high incentive to cheat. Apparently there are 3rd party services in which a human virtually monitors the test taker via a webcam, but they're really expensive and we don't quite have the budget. We still need to make it as hard as possible for a user to game the system. Some of the things we suspect they might try are:
Getting someone else to take the test for them (a pinch hitter).
Taking the test multiple times with different profiles to practice
and gain an unfair advantage.
Taking the test alongside friends or while in contact with a friends
to tell them the answers.
The question order will change, as well as the order of the answers. The test will be timed, and an "open book" format, so we're not really worried about the user looking things up online, but we can't have them sharing their screen and having others assist them. So the main concern at this point is ensuring that the user is, in fact, who they say they are (and not someone else).
Here are a few of the security measures we're considering:
Requiring the user's device to have a webcam, which we'll activate and either record/photograph the user during the test (with the user's consent of course).
Asking users to verify an arbitrary bank deposit amount (presumably via PayPal). There's nothing to stop them from opening up multiple bank accounts, but at least it's a big hassle.
Really scary terms of use that threaten legal action if the user is caught cheating.
QUESTION: Are there any other measure we can/should take to make sure our test is secure and the results are reliable?
CLARIFICATION: We realize that with enough resources and determination, any security system can eventually be beaten. The goal of this question is not to find a magically unbeatable solution, but to find ways to raise the stakes enough so that it won't be worth it for most users to cheat. In this spirit, I'd much prefer answers that focus on what can be done as opposed to what can't.
As you know there are many ways of cheating. Your goal is limit the possibility of cheating as much as possible. Cheating in online courses has been a hot topic.
A pinch hitter:
This type of attack can be conducted a number of ways. Even if you have a cam looking at the person, the video that the test taker is seeing could be mirrored on another screen. A pinch hitter could see the question and just read him the answers or otherwise feed answers the test taker in a covert channel.
Possible counters to this attack is to also enable the mic to see if they are talking to anyone. You can also record the screen while they take the test. This could prevent them from opening a chat window or viewing other unauthorized content. (Kind of like the Elance tracker)
user verification:
In order to register the person should attach a scanned copy of their photo-id. This way you are linking a photo of the person to a unique identifier, such as a drivers license number. Before the person starts taking the test, ask the user to look directly at the camera and make sure you get a good image of them that can be verified against their photo id.
A simple attack against this system is to use photoshop to modify the id. To make this attack more difficult you could verify their name against a credit/debit card transaction. The names should match on both cards.
An evercookie could be used to track machines to see if the same computer is being used. This could happen though legitimate reasons, but it could also be used to flag tests for further review. A variant on the evercookie is to drop a file with a random value or set a registry key with a random value to "mark" that machine.

What should I do when my boss tells me to make passwords the same as usernames by default in our software?

My boss is against requiring our users to have secure passwords, even going so far to request they be setup by default to have passwords the same as their username. What should I do in this situation? What would you do?
Update - Some users have brought up the question of whether the application needs high security. This isn't credit card information for example but does include sensitive information and a mailing list management and sending functionality.
Make the best case you can for strong passwords and then, unfortunately, if they do not see your point of view either do what they asked or find a better job.
What you're told.
...
Then respecfully let the superior know in writing what problems that will cause.
Do not CC anyone. This is my opinion, of course. If you CC it will look obvious. You really just want security but you have to cover yourself. You don't have to be a horse's behind about it though.
Keep it in your sent box, print it, whatever, if you are truly concerned.
edit - You do what you're told unless it is some sort of question of moral turpitude. Then you simply document what you did and why you did it. Just remember that if you do not document it - it did not happen. Documenting is something you should always be doing.
As a compromise there are way better defaults, like using the user's serial number, year of birth, initials, some combination, depending what you have on hand. Not the most secure but not the least either.
Does your application require high security? If the data controlled by your software is not sensitive and the risk to the user is low, perhaps you really don't need strong passwords.
If your app does pose a significant risk to the user if passwords are allowed to be weak, you should make that case as best you can, in writing. If you can quantify risk and liability, do so, but ultimately you will have to leave the decision up to your superiors.
There's nothing wrong with a default password the same as the username provided that the system requests that the user creates a new password the first time the user logs in. You then allow anything as a password if there is low security requirement. If you're handling sensitive data then password strength needs to be of an appropriate level. You haven't said what data you're hiding. There's no point in having super strong passwords (12 chars, lower case, upper case, digit and symbol and no words from dictionary) if it's an intranet based time tracking system. If you're accessing something like a tax record database then you'd need at least two level authentication - string password and one time key generation.
You should hit him hard. Explain him/her what sort of bad publicity might happen because of this, also depends on the data, data protection act and similar stuff can actually cause serious liability. Basically doing it such can be considered as a software defect therefore company can be responsible for the results.
Basically you need to give him a reason which will bite him, scare him. That's how you sell security and insurance :)
If you boss can't figure out such a simple thing and can't trust guys like you at the end, maybe you should start looking for a new place which you can actually use your own potential instead of dealing with these sort of issues.
This is poor security.
If it can result in, for example, identify theft for your users, then you have a very serious social responsibility to improve the security. You are essentially dealing with people's lives. Go to your boss, go to his or her boss. Print out these comments and bring them along. Go to your legal department and tell them how much exposure this causes. If your company was dumping toxic waste whistle blower laws would apply. Personal information and identify theft is no less serious. Do everything in writing to cover yourself and to provide a paper trail of evidence for the lawsuits that will surely follow. Don't allow your company to deny any knowledge of the risk after the fact. Companies that knowingly implement horrible security that results in identify theft should fail in the market place and deserve nothing but shame, ridicule and failure.
If on the other hand this poor security can result in comparatively minor things then your your effort to improve the security can also be scaled back from what I describe above.
Email him your concern (in a non-aggressive way). Give the logical attack vector, reveal what will be exposed. Close by asking for his confirmation taht this is his instruction. Then send to him (only him, as previously suggested)
Email archive both your original email and his confirmation. This will cover you if something happens.
Argue the case for having stronger passwords but also make a compromise. Have the passwords as defaulting to the username with certain letters replaced with numbers perhaps? This all depends on the system as well. If this is an internal system, it could be quite hard for somebody to gain access to the system & do any harm.
Do what your boss says, but make the passwords expire within a relatively short time period.
I would put together a summary document on password policies, benefits of strong passwords, etc and submit it to him for review and try and make it part of company policy. If they still don't like it then do what they ask, as they are the end client and you have done your part to educate them of the pitfalls.
why using user/pasword in the first?
to log user activity?
the operating system asks for it?
if you want to connect an action (whatever) with an user, I as an user would require that my password be safe!
if your boss is afraid, that he may loose "knowledge", if a user is away, and he needs to get access to that uesers data, require everyone to write down his password in a sealed envelope.
if your boss does not trust you, kündige!
Peter
I would consider what is behind the request to have it that way first.
Is it really an active user with username+password what should be being set up in the first place? i.e. perhaps the user should be receiving an email with a link to activate :)
When does the sensitive information comes into the system? Assuming it is input by the user, just have an activation step where the user changes the password (or is the first time (s)he has a password for that matter).
Notice that if you are working with sensitive information, it is likely there is a law relating to it. I would also look into that, if it is illegal it makes for a strong case, and in that case you should Really consider saying plain no (explaining the reason first of course).
Did he say they had to be all lowercase...
Did he explicitly say they had to not include numbers...
You should hack into his account. Then he will know why username=password dont work.
I've run into this before, where they didn't want to use a secure password &/or lock down their computers.
Then it happened our website had been hacked into (not b/c of a password breach, but b/c of flawed component/module for the CMS that we used - but that's a different story) and in a few different occasions, people have logged into the exec's computer to view a few inappropriate things.
The reason for this explanation is to say that it wasn't until this and a few other case studies that I brought to their attention that they understood just how important it is for secure passwords.
As a solution, you may try to do some research on case studies where a breach has occurred on systems or sites where the information stored or protected wasn't terribly important, but the damaged cause and money it took to recover was substantial - such as someone setting up a phishing scam on your site, the holding hostage a server or site & having to wipe clean the whole box to start over, or some other type of breach.
Anyways, take it for what it's worth.
A few things come to mind that you might want to share with your boss -
The biggest security threat isn't outsiders, it's the folks you work with. If there has been someone fired with cause since you've been there, bring that up with your boss - "What if XXXX had access to other people's accounts?" That person many not steal data, but they may try to vandalize the system or mess with data out of spite. Or could they even share that data with a competitor?
Propose a somewhat stronger default as a compromise - username and 4 digits of home phone number. It's not much stronger but it does make guessing a little harder.
People can make fairly secure passwords by using mnemonics. However, you need to train people in how to do that. Offer to hold a session with your users on how to create secure passwords. Honestly, it's not just good for where they work but for anyone who shops or banks online. Something that's easy for IT people who have to juggle multiple passwords may be harder for others.
BTW, I found a nice javascript generator of mnemonic passwords.
http://digitarald.de/playground/mnemonic-password-generator/
I've found situations where a password is shared by several people, because sometimes security is less important than other stuff. Specially in intranets.
A solution can be to store the IP address of each user. It's a security measure closer to security cameras than to locks, but it might be enough for what your boss has in mind.
Slough may be onto something - but it might be too harsh.
Maybe take a combination approach.
Do what`s asked - but when presenting it, make sure it breaks, or you have some mechanism that will show how or why it is not a secure approach. (This will go through a review process before being implemented right?)
Also find any documentation that describes "best coding practices" from respected industry peers either in books or online or even office colleagues that may be able to back up your point of view. Present your sources, and if their ignored, you've done your duty and due diligence, and the final outcome will rest on the superiors shoulders.

What are the core essential features of a bug tracker software? [duplicate]

This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
What should a good BugTracking tool be capable of?
Although there is a large set of features that a bug tracker can have I feel like it is a little overkill and was considering rolling out my own solution. With that being said I didn't want to remove any core functionality that might be used frequently with existing solutions.
The ones I can think of so far:
- creating bugs
- assigning bugs
- closing bugs
- adding description to the bug
Thanks!
Communication between the developer and the user.
Ability for the user to assign certain bits of information such as severity (how much that bug relates to them).
Ability for the developer to override that priority and, if possible, give a reason.
Ability to assign tasks to a developer.
Ability to sort between bug, enhancement, and feature request. The difference between an enhancement and feature request is very subtle but VERY important.
Ability to attach files (such as screen shots)
Ability to have custom fields (such as being able to select which OS, which service pack level, application version, etc).
Ability to have custom user profiles which also give detailed information about their hardware. It's also nice to be able to have the users phone number (if they are on your LAN) so you can ask questions, if needed.
Privacy. Some items, such as security exploits or information that deals with financial information, will need to be kept secret. Even OSS does this from time to time until they can get a patch ready. Everyone has their own rules.
Ability to show the changes between revisions so you can email out a Change Log so users know what you have and have not done.
Reminders about which items are left undone and are assigned to you / unassigned at all.
That's all I can think of...
A good search engine.
It's amazing how many bug tracking products that cost thousands of dollars get this horribly wrong.
Without a really decent search your bug tracking is more like a "bug logging" - log and forget - system which is pretty much useless.
create a bug
close a bug
this is sufficient for closure over the life-cycle of a 'bug' entity. Whether it is enough features for your purpose is another matter.
Take a look at the features of Mantis, choose the features that you need, calculate how long it would take you to write them, and then spend your time on something more useful unless you absolutely have to create your own. ;-)
For most systems like a bug tracking one, it's usually not the creation or editing of the data that makes the system useful. It all comes down to how easily you can navigate through the information to 'add-value' on top of just collecting the data.
Think about the people who will use the system, the programmers, managers, etc. For each group of people, what type of information will make it worth their while to come back to the system over and over again. How can you make it easier for them to get this information?
Collecting information is easy, adding value to it is the hard part.
Paul.
A bug tracker is nothing more than a list of things that need to be done.
It can be as simple as a text file in the software's directory to a fully fledged bug tracker with hundreds of users.
Start with what you need to work with, then expand as needed.
Use Jira, you'll be in good hands.
Here are some important features:
Assign priority to bug (e.g. critical, major, medium, minor, trivial)
Assign bug to a specific release in which it will be fixed
Watcher functionality (so you can be e-mailed when the status changes)
Workflow (i.e. who is working on it, what's the status)
Categorization, Prioritization, and Standardization.
And an easy way to query it so that you can reap the rewards of your hard work on the above three.
Also, make sure whatever you do is extensible! We always decide to add/edit our bug templates during the project depending on needs/fires.
There are a lot of great solutions out there, you probably don't need to roll your own.. But either way you're going to have to make the same decisions. We use a solution that allows us to roll our own templates, so at the beginning of every project we revisit this same discussion.
FWIW: When we rolled our own request tracking system, we built it around procmail and our existing internal web authentication system because we wanted it to be extremely unobtrusive to use: we just send e-mails to the developers (using group aliases if we want) and add a "[t]" to the subject to open a ticket. The recipients get a modified e-mail with the original request and an additional link to the web page that displays the ticket and allows them to close it with 1 mouse click. So the most common tasks are performed through the e-mail client (opening, requesting more information, replying, ...), although there is also a simple web interface for searching etc.
It took only a few hours to write and after more than 34000 request tickets in 7 years or so, I guess it's OK to claim that it has only the essential core features:
create a ticket (by e-mail with marked subject)
close a ticket (clicking on the link in the e-mail, then clicking on "done")
all communication goes over e-mail, not through a web interface(!)
people who were recipients or sender of the original e-mail (opening ticket) are notified about closed tickets ("Subject: <old subject> closed by <someone>" + link to ticket in the body, enough information for most people so they don't have to go look which ticket/bug that was etc.)
a simple web interface provides a search function for own/open/sent/team tickets
Notable absent features that might be needed for a bigger development team / more intense software development:
flexible status for the tickets (dupe, wontfix, reopened etc.)
priorities
reassigning tickets explicitly (in our dev team, the e-mail just gets resent to the unlucky guy who has to do it)
adding comments to the ticket that don't get sent to everyone
assigning the bug to a particular version of the software
YMMV, but it has worked very well for us so far, both for bugs and for simple requests that the sender wants to keep track of.
Define bug.
Thinking about that will most likely make you realize that you're gonna spend a lot of time "rolling your own".
This might be a little beyond what you had in mind, but for me, integration with source control is a must-have. To be able to view the diffs between versions associated with a bug/issue is very handy.
Please please please don;t spend much time "rolling your own". Your time is better spent researching and learning to use real tracking systems.
Some to look at
Trac, Bugzilla and FogBugz. The last one has free hosted solution for small (one or two man shops?) companies.
SO has lots of threads about this topic.
Try not to roll your own unless it is just a word doc or a spreadsheet. Any time you spend making your own is a TOTAL waste.
EDIT
Since you won't be dissuaded, then I'll maybe add some things others have not mentioned.
You need reporting functionality - users need to be able to run queries and they should be able to select the fields they want to "view".
Workflow/lifecycle of a defect is also a good feature. (basically a state machine of the states the defect will go through. ) In fact, this is a useful exercise for you to define all your use cases and functionality. Given that you are in college and did not start out as aa CS major, I doubt you will come up with many on your own. Take some time to browse the feature lists and demos of existing products.
Ability for emails to be sent to various interested parties.
Anonymous users able to see a SPECIFIC defect that they entered
Different access levels and authorities (admin, manager, developer, tester, end-user)
Our bug tracking system is one of the two essential links between my company and our customers ("live" product reviews where existing customers are encouraged to suggest improvements and user interface tweaks being the other).
A bug tracking system must, first and foremost, encourage trackable "dialogs" with your customers. It must answer the question "Have you fixed the problem (defined broadly) that I have been having yet?"
It must have (in no particular order):
A short description of the problem or feature request (the title)
Room for an extended description
The ability to attach files/images (screenshots)
The ability to prioritize bugs/features
The ability to categorize entries as bugs, features, inquiry, etc.
The ability to assign bugs/features to areas (UI, database, documentation, etc.)
he ability to assign bugs/features to products (we track bugs on five products)
The ability to assign bugs/features to releases ("to be fixed in version 5.1")
The ability to assign bugs/features to people (developers/writers)
The ability to assign bugs/features to customers (reporters)
The ability to re-assign to a different person (developer)
The ability to Resolve bugs/features (mark them as finished and ready for testing)
The ability to mark resolution status (fixed, won't fix, can't reproduce, etc.)
The ability to Close bugs/features (take them off list after resolution & testing)
The ability to Reopen bugs/features (restore to "Open" if testing fails)
The ability to inform customers the bug has been resolved (e.g. via email)
Date and Time stamp on every step (Open, Resolve, Close, Re-open)
The ability to report on the number of Open bugs! (how close to release are we?)
The ability to show bug reports versus resolutions
The ability to search on bugs/features by date, priority, product, person, etc.
The ability to list and sort bugs for easy scanning!
Those are the things that we typically use in our system (FogBugz). While this may seem like a long list, we really do use every feature that I've listed here!

Forced Alpha-Numeric User IDs

I am a programmer at a financial institute. I have recently been told to enforce that all new user id's to have at least one alpha and one numeric. I immediately thought that this was a horrible idea and I would rather not implement it, as I believe this is an anti-feature and of poor user experience. The problem is that I don't have a good case for not implementing this requirement.
Do you think this is a good requirement?
Do you have any good reasons not to do it?
Do you know of any research that I could reference.
Edit: This is not in regards to the password. We already have similar requirements for that, which I am not opposed to.
One argument against this is that many usernames / ids in other areas do not require numeric components. It's more likely that users will be better able to remember user ids that they have used elsewhere -- and that is more likely if they do not need to include numerics.
Furthermore, depending on the system, the user ids may work well as defaults when connecting to external systems (ssh behaves this way under unix-like systems). In this case, it is clearly beneficial to have one ID that is shared between systems.
Using the same ID in multiple places improves consistency, which is a well-known aspect of good software interfaces. It's not too difficult to show that the way people interact with a system is a user-interface, and should adhere to (at least some) of the well-known interface guidelines. (Obviously ideas like keyboard shortcuts are meaningless if you're considering the interactions between multiple, possibly unknown, systems, but aspects such as consistency do apply.)
Edit: I'm assuming that this discussion is about usernames or publicly visible IDs, NOT something that pertains directly to security, such as passwords.
I would begin by asking them for their specific reasons behind this. Once you have a list of bullet points and the reasons why, it's easier to refute or provide alternatives.
As for general ideas:
This is opinion, but adding a numeral to a username won't necessarily increase security. People write down usernames on post it notes, most users will just add a '1' to the beginning or end of their username, making it easy to guess.
From a usability standpoint, this is bad as it breaks the norm. Forcing them to add a numeral to their username will just lead to the above point. They will simply add a '1' to the end or beginning of their username.
Remember, the more complex an authentication system is, the more likely a general user is to find ways to circumvent it and make their link in the chain weak.
UserIDs? Requiring passwords to be alphanumeric is generally a good idea, since it makes them more resistant to a dictionary attack. It doesn't really make any sense for usernames. The whole point of having a name/password combo is that the name part doesn't have to be kept secret.
If you're working at a financial institution, there are probably regulations about this sort of thing, so it's most likely out of your hands. But one thing you can do is make it clear to the user when he has entered an invalid ID. And don't wait until he clicks submit; show some kind of message right next to the field, and update it as he types.
A few of the answers above have a counter-argument: If the users pick the same username they use on the other sites, then they are also likely to pick the same or similar passwords for the financial site, lowering security.
A reason not to do it: If you impose more restrictions than they are used to on the users, they will start writing down the login information, and that's an obvious loss of security.
Both of the bank accounts I have require an alphanumeric username and two passwords for the online login. One of them also has a image I have to remember. The two passwords have to change once a month or so. Therefore, I have all the login information right here on a text file. (Even looking at it doesn't make any sense; I'll have to go down to the bank and reset my passwords again. That's a grand total of 7 password resets for 6 logins. Talk about security, not even I can access my account.)
it's good if it's in their password (as alas, financial companies like to deny you this security right [i'm talking to you american express]).
username, i say no, unless they want to.
A username will (presumably) need to be quoted on the phone when calling for support so it will be publicised unlike a password. Also, the username field won't be masked out in browsers like password fields are, so it will have much more exposure and get cached/logged in various places, so the 'benefit' of the added security will be undone in no time.
And the more difficult you make things, the more likely a user is to write it down somewhere which again undermines security (same applies for password policies actually, but that's another story!)
I also work at a financial institution and our usernames (both real people and production IDs) are all lowercase, alphabetical, up to 8 characters and I've never considered it a problem... avoids the confusion of 0 vs O, 1 vs I, and 8 vs B - unless you work for the same company as me and are about to implement a new policy...
Adding any feature adds costs. It will take time now to build and test it, and in the future to support it. No feature should be built without a really good reason.
This feature is pointless. Usernames are not supposed to be kept secret, so having strong usernames has no advantage. It is probably worth spending time making passwords (or other authentication factors) strong, but users should be able to communicate their username to other users without that being a security risk.
If your application imposes extra constraints on the choice of user ID then some of your users will have a different user ID for your application than for the other applications in your environment. Note: I'm assuming that this is an internal application (for use by employees) rather than in Internet-facing application.
Having inconsistent usernames adds a number of specific risks:
It will make the audit trail harder to follow (a serious security risk).
It may add cost if you later start using single sign on.
It will cause a bad user experience as users have to remember that this application uses a weird username.

How do you measure if an interface change improved or reduced usability?

For an ecommerce website how do you measure if a change to your site actually improved usability? What kind of measurements should you gather and how would you set up a framework for making this testing part of development?
Multivariate testing and reporting is a great way to actually measure these kind of things.
It allows you to test what combination of page elements has the greatest conversion rate, providing continual improvement on your site design and usability.
Google Web Optimiser has support for this.
Similar methods that you used to identify the usability problems to begin with-- usability testing. Typically you identify your use-cases and then have a lab study evaluating how users go about accomplishing certain goals. Lab testing is typically good with 8-10 people.
The more information methodology we have adopted to understand our users is to have anonymous data collection (you may need user permission, make your privacy policys clear, etc.) This is simply evaluating what buttons/navigation menus users click on, how users delete something (i.e. changing quantity - are more users entering 0 and updating quantity or hitting X)? This is a bit more complex to setup; you have to develop an infrastructure to hold this data (which is actually just counters, i.e. "Times clicked x: 138838383, Times entered 0: 390393") and allow data points to be created as needed to plug into the design.
To push the measurement of an improvement of a UI change up the stream from end-user (where the data gathering could take a while) to design or implementation, some simple heuristics can be used:
Is the number of actions it takes to perform a scenario less? (If yes, then it has improved). Measurement: # of steps reduced / added.
Does the change reduce the number of kinds of input devices to use (even if # of steps is the same)? By this, I mean if you take something that relied on both the mouse and keyboard and changed it to rely only on the mouse or only on the keyboard, then you have improved useability. Measurement: Change in # of devices used.
Does the change make different parts of the website consistent? E.g. If one part of the e-Commerce site loses changes made while you are not logged on and another part does not, this is inconsistent. Changing it so that they have the same behavior improves usability (preferably to the more fault tolerant please!). Measurement: Make a graph (flow chart really) mapping the ways a particular action could be done. Improvement is a reduction in the # of edges on the graph.
And so on... find some general UI tips, figure out some metrics like the above, and you can approximate usability improvement.
Once you have these design approximations of user improvement, and then gather longer term data, you can see if there is any predictive ability for the design-level usability improvements to the end-user reaction (like: Over the last 10 projects, we've seen an average of 1% quicker scenarios for each action removed, with a range of 0.25% and standard dev of 0.32%).
The first way can be fully subjective or partly quantified: user complaints and positive feedbacks. The problem with this is that you may have some strong biases when it comes to filter those feedbacks, so you better make as quantitative as possible. Having some ticketing system to file every report from the users and gathering statistics about each version of the interface might be useful. Just get your statistics right.
The second way is to measure the difference in a questionnaire taken about the interface by end-users. Answers to each question should be a set of discrete values and then again you can gather statistics for each version of the interface.
The latter way may be much harder to setup (designing a questionnaire and possibly the controlled environment for it as well as the guidelines to interpret the results is a craft by itself) but the former makes it unpleasantly easy to mess up with the measurements. For example, you have to consider the fact that the number of tickets you get for each version is dependent on the time it is used, and that all time ranges are not equal (e.g. a whole class of critical issues may never be discovered before the third or fourth week of usage, or users might tend not to file tickets the first days of use, even if they find issues, etc.).
Torial stole my answer. Although if there is a measure of how long it takes to do a certain task. If the time is reduced and the task is still completed, then that's a good thing.
Also, if there is a way to record the number of cancels, then that would work too.

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