HELP NEEDED (comparing frequencies among two groups)

[css]

Hi everyone,
I would like to analyze whether two slightly differently sized (N=45 and N=55) groups of participants differ in their observed frequencies for 4 types of "events". The events are errors in a memory/ recognition task for 4 different kind of stimuli (that is, I asked participants to declare whether or not an item has appeared or not in a previous phase of the experiment and I count as an error when they say that the item did not appear, but I have 4 different categories of items and I want to know whether or not groups differ at each one of these categories). I initially thought performing a chi-squared test of independence and analyze the standardized adjusted residuals, however I am not sure if this is the right approach (as I am dealing with count data).

Thanks in advance for your responses.

 

[hlsmith]

My first inkling was also chi-square or Fisher's exact, but can you post your tables so we can see what data look like.

Thanks.

 

[css]

Hi Hlsmith,

First of all thanks for your fast answer. I attach a table showing the data I am talking about (sorry, I had to do it as PDF because I could not upload excel file). Note that the data are the accumulate frequencies of errors in each group at each stimulus category. If that is not what I should be showing, please just let me know.