topic Re: Calculating effect size in Discussions

Calculating effect size

Sandeep123 — Fri, 09 Jun 2023 00:31:11 GMT

I have a data set of about 2000 patients. There are two groups one with the critical illness and others with known critical illness.

I have done a univariate comparison between the two groups based on a there are age (continuous variable) and a number of other categorical variables like sex or race comorbidities et cetera.

Because of the relatively large dataset most of the differences come back as statistically significant with the values less than 0.01.

The reviewers of my paper however want me to report and interpret standardised effect sizes (Cohan's D or Cramer's V).

It seems to be a pretty simple thing to do it on SPSS.

Cramér’s V - Beginners Tutorial (spss-tutorials.com)

It is possible to do this in JMP? The only documentation I could find online was for doing it in a standard least square model in linear regression

Re: Calculating effect size

ron_horne — Sat, 27 Mar 2021 12:46:12 GMT

Hi @Sandeep123 ,

perhaps this discussion help you calculate it manually if you just need a few estimates.

https://community.jmp.com/t5/Discussions/How-to-get-a-p-value-on-descriptive-statistics-How-to-get-Cramer/m-p/68426/highlight/true#M34835

Ron

Re: Calculating effect size

ron_horne — Sat, 27 Mar 2021 12:49:24 GMT

Hi @Sandeep123 ,

perhaps this discussion help you calculate it manually if you just need a few estimates.

https://community.jmp.com/t5/Discussions/How-to-get-a-p-value-on-descriptive-statistics-How-to-get-Cramer/m-p/68426/highlight/true#M34835

Ron

Re: Calculating effect size

Sandeep123 — Sat, 27 Mar 2021 20:59:27 GMT

Ahhh

so there is no way to get this automated in jmp. Some other marker of effect size may be?

Re: Calculating effect size

Thierry_S — Mon, 29 Mar 2021 12:22:33 GMT

Hi Sandeep,
It looks like there might have been some confusion about your question. The Cohen's D effect size measure is simply the difference between the means of the group you compared divided by the pooled standard deviations. While this measure is not directly available in JMP (at least in version 14.1), there is a JMP Add-in that does exactly what you need: .
I'll continue to dig to see if there is something even simpler to address your needs.
Best,
TS

Re: Calculating effect size

Sandeep123 — Sun, 28 Mar 2021 14:35:44 GMT

yes it is only available as LSM model not in Fit X by Y platform..which is fine. I can use it for cohen's D. Cohen's D is also very simple to calculate by hand.

Problem is with categorical variables..Cramers' V ?

Re: Calculating effect size

Sandeep123 — Sun, 28 Mar 2021 15:13:02 GMT

It seems to me that the measures of association option available in JMP is what I need

It does not give Cramers V but gives Lambda and un certainty coefficient..which seems to be similar

Measures of Association (jmp.com)

Crosstabs statistics (ibm.com)

Re: Calculating effect size

Mark_Bailey — Mon, 29 Mar 2021 16:11:45 GMT

The two measures that you asked about are not available in JMP, but many others are available. See the Help entry. Perhaps one of them might satisfy the reviewer.

Re: Calculating effect size

Sandeep123 — Mon, 29 Mar 2021 18:40:05 GMT

yes .JMP give these measures for association.

Seems from the help menu that lambda and uncertainty coefficient best suit for nominal data.

The values however are very low for lambda it is mostly 0.0000 even when p value is < 0.001

Since i have not seen reported in literature, is it expected for them to be this low in retrospective clinical research

Re: Calculating effect size

Mark_Bailey — Mon, 29 Mar 2021 18:52:11 GMT

The p-value may be used to assess the strength of the evidence against the null hypothesis (no association or measure is zero). The measure of association is used to assess the strength of the association (similar to measures of correlation). So you have strong evidence that the measure is not zero, but it is a weak association. There is a lot of uncertainty in the response even when you know a given category.

You know how to calculate V yourself from the reply above. What value of V do you get for the same association that you analyzed in the picture above?

Re: Calculating effect size

Sandeep123 — Mon, 29 Mar 2021 18:59:06 GMT

Manual calculation of Cramer's V from this data from the description below

Cramér's V (ibm.com)

would be 0.01..

Re: Calculating effect size

Mark_Bailey — Mon, 29 Mar 2021 19:51:24 GMT

So by most of these measures, the association is weak.