# March 27, 2021 (Part 2)

March 27, 2021•299 words

This is the second entry of the day.

I started to design some midterm exam questions. After a while, you run out of questions to ask. I cooked a steamed salmon and put some squid balls into some fish stock I kept for some time.

I did not do a lot of research today. I spent time reading papers related to non-probability sampling. I think I might have an idea that can be merged with a current master's student's interest in this topic. There is actually some very underrated stuff in this literature on combining non-probability samples (passive and cheap, but not representative) and probability samples (active and expensive, but can be made representative).

I am not sure I was able to relax, perhaps got some downtime. I also phoned the hospital to ask about getting a complete physical.

I also talked with my family for an hour or so, talking about cats, covid, and current quarantine measures.

I spent quite some time working out the final set of regulations for the PhD process for international students and drafting emails here and there. These tasks always take a lot of my time.

I also got a contribution from a student regarding matrix calculus. I tried to avoid using matrix calculus in class because I teach a heterogeneous bunch of students. I think I may have remarked too much in class of my aversion towards matrices in my older age. I used to like working with the algebra of these models but there was a point where I just got turned off. In my master thesis, I even worked on a lot of these matrix algebra results to study mixed estimation and pre-testing. Now I am struggling to remember why I started to get averse to too much matrix algebra.