NAN in post-hoc test
Dear JASPers, I am doing a repeated measures ANOVA analysis, but for some reason many (but not all) of my post-hoc tests show a mean difference, a SE, a statistic, but then a NaN for the p-value (see below).
Could you please help me understand why there is a NaN?
thank you
martin
Comments
sorry, I now saw a similar post. I ran my analysis on 0.9.1, so I'll try it on 0.9.2 and re-post if needed (sorry!) :-)
Dear All,
still got the NaNs above in 0.9.2. Any advice?
Cheers
Martin
Hi Martin,
I'll ask the expert in our team. We are nearing a new version, so it would be great to see this fixed (if it is a bug).
Cheers,
E.J.
Hi Martin,
Due to the Scheffe and Tukey corrections not being suitable for RM factors, we have decided to not display those and clarify this with a footnote in the table. However, I will change the way it is being displayed, since NaN is ususally an indicator that something went wrong in the analysis.
For now, I would advise you to use another p-value correction, such as Bonferroni or Holm.
Kind regards,
Johnny
Hi All. I've encountered similar issue of NAN when running Games-Howell post-hoc on a one-way ANOVA using JASP 0.9.2. However, in my case this only seems to be associated with some values and with this particular post-hoc. All data has the same number of repetitions (only 2 data points for each group). As can be seen below, some pairwise comparisons come back with NAN while others are returning a value. Both Dunn and Tukey give values for all comparisons.
Hi HMSTAT,
To calculate the p-value, JASP uses the ptukey function from R (see also here: https://rpubs.com/aaronsc32/games-howell-test).
It seems that for most groups, the df is very low due to only 2 observations per group, which breaks the ptukey function. If you want, you can send me your data set and I will look into this a little bit more (you can send it to j.b.vandoorn at uva.nl), but I think your n per group is simply to low.
Kind regards,
Johnny