I think I understood your point that we cannot look at just one category. Thank you very much for your help.

Sorry for my poor explanation. We have two group, say the group A and the group B. We would like to compare that the statistical difference (p-value) between these groups in term of the following age distribution at first. 1. less than 20, 2. 21-30 years, 3. 31-40 years, 4. 41-50 years, 5. more than 50 years. We found a significant difference among the age distribution in the group A and B using Chi-square test. We then tried to find p-values of each category by creating dammy variables in chi-square test. Is this acceptable way to find p-values of each category) using dammy variables?

Thank you for your message. I initially use cross-table to find out statisitical difference of the age distribution between the group A and the group B. I found out a significant difference between the groups. I then tried to find out the diffirence in each p-value using dammy variables (0 and 1) in age distributions with chi-square test. My question here is whether chi-square test can be used to find out the statistical difference in each categorical variable under these situation.