Dear All,

I want to ask you what is the most appropriate test for testing significance in difference in means.

I look at selected key measures for firms on a period from 2013-2017 in one sector in a specific country. The firms are sorted in two groups: small cap and large cap.

The small cap group consists of 10 firms. The large cap consists of 17 firms.

When for instance looking at the ratio - return on equity - i get a mean of 5.2 percent for the small cap group and 10.1 percent for the large cap group.

What is the appropriate test to test for significance in the difference in the mean (10.1-5.2).

Number of observations for the small cap group is 50 (5 years times return on equity for 10 firms). The number of observations for the large cap group is 85 (5 years times return on equity for 17 firms).

Is this still a sample? Because it is 5 years only? Also what test should I use? The sample number is also different.

If anybody have an idea eventually a reference to a lecture book, it would be of great help.

Thank you in advance.

Best,
Anders