To see if fish species distribution is dependent on area, I have collected fish sample for one year from four selected sampling site of a given lake. Thus, ten fish species were recorded from all sites. Hence, I used a two way classification chi square to see the difference of the species distribution among the sampling sites and I had got significant difference. However, could not able to see which site is significantly different from which other sites. Therefore, is there anyone who can give me some explanation about this.
As long as you there are significant differences of the species distribution among the sampling sites, you may use one of the post hoc tests, such as scheffe test if equal variances are assumed.
One way is to analyze the component 2xn tables. In this case you compare Site 1 with Site 2, and in a separate test compare Site 1 to Site 3, and so on.
Since you are conducting multiple tests, you may want to adjust the p-value or alpha values to deal with the "inflation of type-i errors."
The example here may be helpful:
http://rcompanion.org/handbook/H_04.html
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