The Chi Square test would be appropriate if you could break your respondents in two groups,

large and small companies for example, or perhaps growing or stable companies.

But this is a problem, because company size is an analog value.

You could pick some threshold so that [greater than ==> BIG] and [less than ==> SMALL].

But this arbitrarily and unnecessarily smears your data.

A quantitative and more convincing approach if you have enough data would be to plot the probability of

a company joining a portal versus company size. You might be able to do a linear regression and get a good

correllation coefficient.