Correlation between the same test

[#1]

Hello

I want to find r correlation between the same test but the different periods.

for example:

I scored tests in April and October and I need to know the correlation between these periods.

I find multivariate function in JMP but I need result in table not in graph.

I need receive 2 columns Name of test and Correlation for each test.

In excel I can use CORREL function, but didn't find something similar formula to do it.

[#2]

Hi @Dennisbur,

You have made almost all the work by using the Multivariate platform.

With the same table format than the one you show, you can select April and October as your "Y" columns and Test as your "By" variable.
Once the platform is launched, right-click on the results from "Correlations" panel and then you can either "Make into Datatable" (to have a separate table with correlation coefficient by test) or "Make combined Datatable" (to have a table with both correlation coefficients).

You can look at the example tables in scripts (one for each separate test "Correlations_Test", and one for combined datatable "Correlations_Table").

I hope this will help you,

[#3]

@Victor_G has provided the correct answer, however, just for grins, I have provided how you could generate the correlations in the form that you used for your Excel model. 

If you add in the 2 new columns you want and type in the Values for the column you indicated you  wanted to name "Name of Test", you could then add the following formula to the second column you named as "Correl" to get your results.

dt = Current Data Table();
If(
	Row() == 1, cor = Correlation( dt[Index( 1, 3 ), 2] || dt[Index( 1, 3 ), 3] )[2, 1],
	Row() == 2, cor = Correlation( dt[Index( 4, 6 ), 2] || dt[Index( 4, 6 ), 3] )[2, 1],
	cor = .
);
cor;