In Tableau when I go to Analysis > Trend Lines > Show Trend Lines, why does it show 3 trend lines?
What does this mean?
Or can you tell me to google to figure this out? I'm stumped ???
The lines above and below are confidence bands:
http://onlinehelp.tableau.com/current/pro/desktop/en-us/trendlines_add.html
Tableau confidence bands show upper and lower 95% confidence lines by default when you add trend lines.
You can turn them off by clicking "Show Confidence Bands" in the dialog.
The upper and lower lines in tableau linear trend lines are actually the confidence lines that shows the variation of the trend along the whole graph.Means, closer the confidence lines to the main trend line, means more closer is the trend line towards the main graph or plot. So, these are actually the helping lines.
Related
I have a list of years from 2019-2098 that I want to be the x-axis values. The y-axis will be from 0 to 1 for probabilities. The line graph will measure the survival probability curve in relation to years. The issue is that I need a vertical line to reside on the mark for year 2042. Is there a way to do this? Everything I have found online doesn't work! The photo is what I get from doing an online example. It produces a vertical line but not in the correct spot.
You could add a separate data series that consists of (2042,0) and (2042,1).
Graph them as a scatterplot on top of your existing data. If needed, go to Change Chart Type and set the appearance to connect the two points with a line where the points don't show. Example: Scatter plot without points showing.
I created a plot in Tableau with a line of best fit using the "Trend Line" feature under "Analytics". This plots a line of best fit, with optional confidence bands around that line.
Here's a screenshot of my plot
My question is: how do I edit how wide or narrow the confidence bands around the line of best fit are? I read somewhere that they default to 90% or 95% confidence. I want to be able to widen or narrow those lines by increasing or decreasing the confidence. My goal is to make the bands more narrow.
I couldn't find how to do this online after a lot of searching. Any help is much appreciated!
Thank you
The confidence band for trend-lines cannot be altered in the same way they can be for other trending analytics (such as forecasting). In fact, within Tableau trend-line confidence bands cannot be altered at all.
In order to make the bands more narrow you would need to find a better fitting trend-line. To do this you can right click on the trend-line and click edit and play around with logarithmic, exponential & polynomial options.
I believe that the trendline confidence bands in Tableau cannot be altered because it represents the potential error as calculated from the StdError. This is the deviation around the trend-line from actual data points and is unrelated to confidence %s.
You can see this by right clicking on the trend line in Tableau and clicking 'Describe Trend Line'. This will open a dialogue which describes the derivation of the trend-line. What you will find is the Confidence interval will be drawn the width of the StdError.
I have scatterplot in Tableau, and I displayed trendlines. However, I cannot understand why there are three of them.
When I research this on Tableau, they say upper line is upper 95% confidence, and lower line is lower 95% confidence.
When I think of confidence levels, I think if there are 100 black and white marbles and I take a sample, and see the ratio, I can say 95% of the time, white marbles will be 40% to 60%
And to create confidence bounds, 92% to 98% of the time, white marbles will be 40% to 60%
But I'm having difficulty translating this to tableau trendlines. Please advise.
Think of your data set as just one random sample drawn from a larger population of possible data sets. You could have sampled another time or place or in a parallel universe.
If you could build a scatter plot for the entire population, it would have a best fit trend line also. You can think of your trend line as a sample trend line attempting to estimate this true population trend line.
Now imagine you actually did collect many different sample data sets from that same population. Also imagine you used identical procedures to create scatter plots and trend lines for hundreds or thousands of these data sets (samples). Different samples would lead to (slightly?) different trend lines in each plot.
The confidence bands are constructed in such a way that you can expect them to enclose the true population trend line in 95% of your samples.
You are using statistical inference to estimate the confidence in the population trend model parameters. All based on the Central Limit Theorem.
I'm having a line graph of production waste corresponding to four different production sites. However, I want to include a trend line (regression) in the same graph. This regression should conduct a trend line of the total production waste of the production sites.
I.e. if production site 1 through 4 has a production waste of 2 units each month, I want the regression to be a flat line at y = 8.
Is this possible? I'm using Excel 2010.
EDIT: I've realized that it is not possible to make a regression line without converting the regular graph into a scatter plot first (or is it..?). However the initial question remains.
Add the total of all sites as a data series to the line chart and then add a trend line for the total series. Format the total series to show no line and only the trend line will be visible. In the screenshot the dotted line is a polynomial trend line on the total series, which has been hidden by formatting with no line.
On this JMP plot
found here
Does the horizontal grey line represent the overall mean or median (or something else)?
The gray line shows the survival plot on your diagram.
When you select Show Points and Show Combined, the survival plot for the total or combined sample appears as a gray line. The points also appear at the plot steps of each group.
http://www.jmp.com/support/help/Survival_Platform_Options.shtml
See also: http://www.jmp.com/support/help/The_Survival_Plot.shtml