Quartile lines on a line graph

[#1]

Hi, can anyone help? I was trying to add in upper and lower quartile lines into a line graph on graph builder on top of a mean line. 

On my X axis I have weeks of they year (time) and my Y axis is weight gain. With the mean line I can see the trend of the population, but I also what to see the trend over time of the top and bottom quartile. 

Thanks!

[#2]

I tried to add a temporary column in Graph Builder but I ended up adding a new column in the data table for each quartile. Then add them together to the Y axis and change the plotting element to Line.

I am using Big Class for my example. Here is the formula for the first quartile:

Col Quantile( :weight, 0.25, :age )

Here is the result:

[#3]

You can get the information you want, by specifying an Interquartile Range Error Bar.  This may get you what you want