How to draw conclusion on a Population based on a Sample
You always run your study based on a subset of the entire population, you intent to generalize on. External validity refers to the extent to which you really could do so. This in turn depends on the sampling methods you where using.

All slides to the entire series can be downloaded for free here: https://armintrost.de/en/professor/digital/social-research-methods/

#13 Nominal, Ordinal, Interval and Ratio Data

This podcast covers all relevant aspects around research methods in social science. After a short introduction all steps will be considered from defining the hypothesis and research question to academic writing.

All slides of the entire series can be downloaded here: https://armintrost.de/en/professor/digital/social-research-methods/