Everything depends on your research questions and purposes. With that said, the gold standard in quantitative research is randomized and of sufficient power for the sampling frame/population. Qualitative research varies, though small samples and homogeneous are common [purposive is often used, but qualitative can also be many kinds of samples]. Again, look beyond rules of thumb--think sampling frame and population.

Quantitative is about 'width' and numbers. This usually means a larger sample size or population with scaled questions. Qualitative is more about 'depth'. Hence it is about a smaller sample but using open ended questions to gain deeper and richer data. Both methods will be dependent on your objectives.

Thank you very much, sir.

In quantitative research generally we go for Random sampling ( Probability sampling) and large sample. In Qualitative method we go for non probability sampling methjod, like purposive sampling, and small sample.

Thank you very much for the information, it is quite enriching.