The sampling frame is a list but not every list is a sampling frame

Yesterday and today, I spent some time marking the in-course assessment (ICA) for my course (the teaching term is over next week $-$ yay!).

The course is called “Social Statistics” and it’s intended to deal with surveys and sampling. However, since I inherited 3 years ago, I’ve tried to include more material on missing data and some stuff about clustering too, with a view to teaching some modelling.

For the ICA, this year I decided that I would randomly group the students and have them do a quick survey. Admittedly the time was quite short (only 1 week from assignment) and when they got the ICA we were basically only halfway through the course, so they didn’t really know about important stuff (such as more advanced sampling methods, or sample size calculations).

All in all, I was impressed by the creativity of most groups in selecting the topics for their surveys. Some groups did a very good job getting all the parts right $-$ stuff like realising that you can’t really extend your inference to a much larger population if you only have a small convenience sample (which may still be a reasonable choice, given time & resources constraints), or going out of their way to find a proper list so that they can use simple random sampling.

A few groups, however, used the list of emails for all the students enrolled in the class (which could be a sampling frame $-$ if the target population were the class!) as it were a sampling frame for a much larger target population (eg the whole of UCL students).