1.   Another, more prolonged and more significant, concerned the very foundations of variable analysis, and by implication the explanatory survey, namely its empiricist inspiration.

2.   Unfortunately, in a number of respects explanatory surveys failed to match up to the strict requirements of the logic required.

3.   In most cases of explanatory surveys it is perhaps less appropriate to speak of samples at all in the strict sense.

4.   What explanatory surveys require are cases which possess characteristics relevant to the problem of the research.