Each category contains count data, however I have a different number of observations on each day - some days have 10 observations, some 12, some 21.

I want to test to see if the day of the week has an influence on the count and decided a Chi-Square test is most appropriate (...good choice?).

I am unsure what to use as observed and expected in the test. Should I average the count on each day and use this as the observed values? Or should I sum the observed values on each day and then adjust the expected values to reflect the difference in exposure?

Any help would be really appreciated,

Thanks