

Note that one value is blank. It is fine to have some missing values, but you must have at least one value in each row for each data set.
The following table cannot be analyzed by twoway ANOVA because there are no data for treated women. Every cell must have at least one value.
If you are entering mean, SD (or SEM) and n, it is fine if n is not always the same, but ANOVA won't work if you leave n blank or enter zero.
There are two different situation regarding missing values and repeated measures twoway ANOVA:
•Prism can compute repeated measures twoway ANOVA fine if treatment groups have different numbers of participants, but each participant (experiment, litter, ...) has data at each repeat.
•Prism (starting with Prism 8) can also do the equivalent of repeated measures twoway ANOVA if values at some repeats are missing, so long as not too many points are missing and they are missing completely at random. If some values are missing because they would have been too large to measure, then any results would be meaningless because the missing values actually represent the largest values in the table. But if a few values are missing completely at random, Prism uses a can fit a mixed effects model.