# How should I interpret the results of corrplot (variable correlations plot)?

I am trying to look at correlation between different variables. I used MATLAB's corrplot function and got the attached results. The function's documentation doesn't provide detailed description of the plot. How do I interpret these results? What do the blue bars show? Why are they the same for both results A & B? What does the red line show? What more can I say about the two results? Apart from no correlation in A & Positive correlation in B)? my data matrix is 64 x 2: what are the values on the $y$ and $x$ axes of the plot?

• I don't use MATLAB but a quick Google finds explanations, e.g. uk.mathworks.com/help/econ/corrplot.html Histograms appear on the principal diagonal; otherwise pairwise scatter plots are given. However, watch out as the same name appears to have been used for other functions. – Nick Cox Dec 20 '15 at 23:55
• In addition to what Nick said (+1) : The red lines show (I quote the doc verbatim) "the slopes of the least-squares reference lines in the scatter plots are equal to the displayed correlation coefficients." What exactly don't you understand from MATLAB's doc? – usεr11852 Dec 20 '15 at 23:59
• uk.mathworks.com/matlabcentral/fileexchange/35674-corrplot/… appears quite different. – Nick Cox Dec 21 '15 at 0:03
• @NickCox: The later link from MathWorks FileExchange is a user-generated function. Realistically this is not what the OP uses. The screen-shots provided by the OP: 1. match very well with the screen-shots in the MATLAB docs; 2. are very different from the user-generated function publishers example screeshot. – usεr11852 Dec 21 '15 at 0:17
• @usεr11852 Thanks; that's what I was guessing by analogy with software I know better, but I wanted someone closer to MATLAB to confirm it. – Nick Cox Dec 21 '15 at 14:35