I wrote these few lines as a translation from Czech to English. I don't consider myself a good translator and would like to ask you to check whether what I wrote is good natural English. I'm not concerned about stylistics; I know that almost everything can be improved as far as stylistics is concerned.

Two groups of the elderly were chosen for the purpose of a questionnaire inquiry. Both of these groups have in common the fact that their members live in their own household. What these groups differ in is whether they use social services or not.