## Estimating Population Size: Animals and Web Pages

Thinking about all of the things in the statistical world that we can estimate, the one that has always perplexed me is estimating the size of an unknown population $$N$$. Usually when we compute estimates based on samples, we involve the size of the sample $$n$$ somewhere, thus we take “size” for granted — the size of a sample is known. We also make inferences based on sample statistics using theory such as the Central Limit Theorem, but seem to never care about the population size $$N$$, we either know it, or assume it is infinite. But, in fields like ecology and environmental studies, this attitude of gluttony is dangerous!

In the summers I spend a lot of time in the Eastern Sierra where there are deer and bears. These animals are so large that we cannot consider their population in the area to be infinite (like we may with ants or bacteria). A matter of fact, one of our local animal behavior specialists knows the exact number of bears that live in my mountain community. I always had just assumed he spent all day tracking down the local bears and marking them with radio collars. There must be some […]

## Ph.D. Defense Post Mortem and Advice for Others

NOTE 1: This is part 1 in a series that will probably contain 3 or 4 parts. Then I will return to the usual data science etc. posts. NOTE 2: This post was intentionally delayed until I received final approval on the submission of my final dissertation.

On March 14, I passed my final oral defense for my Ph.D. in Statistics.

It was the moment I had been waiting for. The moment I dreaded for so many years and the moment that I thought would never come. I had very few days and times to choose from. It came down to the 13th (bad luck?) and the 14th (Pi Day). My defense began at 10am and was supposed to take a max of 2 hours. I left home around 7am to be sure I arrived in enough time after what could be a long ride. I arrived at 8:45am after sitting in rush hour traffic for almost 2 hours. I printed color copies of my slides and four copies of my dissertation and set up each committee member’s spot nicely: one water, slides, dissertation, a plate and a napkin. I placed a big tray of color-sprinkled cookies in the middle […]