Normal quantile plot for different variables

[#1]

Hello, 

I have data which correspond to different cases (resistance values for different structures). I want to make the normal quantile plot for each case and see all cases in the same graph (each case with different marker or color, for example) in order to observe directly the differences and make comparisons.

Is it possible? I try grouping by structure in the option "by" but I obtain one different graph for each case.

Kind regards,

G.

[#2]

@shrirams   I can give you explicit instructions to my less than elegant method of creating the Normal Plots (and Pareto Plots) for the whole plot and sub plots of a split-plot design.  Not sure it is appropriate to post this here, but if you send me a private message, I'll be happy to help you out.

[#3]

Your A & B make up the whole plot.  The WP has 3 DF's.  They are A+B+AB. I don't know what the sub plot is. I could be of more help if you provide the number of factors and resolution in the sub-plot.  

I have attached a pdf of instructions for analyzing such a split-plot design.  I call this an efficiency split-plot...The restriction has nothing to do with difficulty in changing factor levels, but due to the desire to increase the precision of the WP and the SP while minimizing resources.  In the example attached, the experiment has 31 total DF's.  The whole plot is created by factors S, P & V (full factorial). WP has 7 DF's: S+P+V+SP+SV+PV+SPV.  The sub plot is created by factors T & t (full factorial).  SP has 24 DF's: (T+t+Tt)(1+WP).

Y=WP+SP.  Let me know if you have any questions.