The idea with A is that you will get a more representative sample if you follow up specifically with the people who did not initially respond. Yes, some will never respond, but the ones that do answer will increase the quality of the data, moreso than an additional random sample. The people who did not initially respond are more likely to be busy/lazy/unengaged, and without as many responses from that cohort, the data will be skewed.
That seems like a pretty small potential confounder. It doesn't seem to bother the US Census, for example, that they get some people's response via mail right away, and others they have to go knock on the door and pester them to respond. Any random sample of people is going to include some who really like answering questionnaires, and some who hate it or are too distracted or busy. Designing a survey where you plan to contact people multiple times seems perfectly normal and reasonable.
> That seems like a pretty small potential confounder. It doesn't seem to bother the US Census, for example, that they get some people's response via mail right away, and others they have to go knock on the door and pester them to respond. Any random sample [...]
The decennial census is not a random sample, though the Census Bureau does sruveys that are random samples separately.
The Census uses this technique when doing random samples. One of the ways to improve accuracy is to put a lot of effort into contacting a random sample of non respondents which simply isn’t viable at scale.
If you want social science research checkout the General Social Survey by NORC. They have been following the same cohorts of people for the last 50 years with biannual surveys. The data is open to view at https://gssdataexplorer.norc.org/
Option A is absolutely the worst choice. The non-responders have already selected themselves into a non-random set, and making a request to them alters the entire experiment.
Why would this be expected to improve sample quality? You want a random sample, not a non-random piece of a non-random subset. Non-random sampling just introduces more confounders and makes your sample quality worse.
