Sunday, 13 January 2019

Statistical Vocabulary Crossword Puzzles

I've expanded the statistical thesaurus again, as well as made some crossword puzzles from them, for vocabulary study.


Saturday, 29 December 2018

Degrees of Freedom, Explained


You can interpret degrees of freedom, or DF as the number of (new) pieces of information that go into a statistic. Using examples from this video [https://www.youtube.com/watch?v=rATNoxKg1yA , James Gilbert, “What are degrees of freedom”]

I personally prefer to think of DF as a kind of statistical currency. You earn it by taking independent sample units, and you spend it on estimating population parameters or on information required to get compute test statistics.

In this article, degrees of freedom are explained through these lenses through some common hypothesis tests, with some selected topics like saturation, fractional DF, and mixed effect models at the end.

Saturday, 15 December 2018

We read this: "Your bones".

This is review of the book  “Your Bones”, a medical book aimed at the general public by Lara Pizzorno and with Jonathan V. Wright. The review was co-authored with Gabriela Cardillo; she provided the body, medical expertise, and main content and I edited and added the criticisms and asides at the end.

Monday, 12 November 2018

Four OJS manuscript reviews, 2015-2018

Here is a dump of the remaining reviews I made for Scirp's Open Journal of Statistics from 2015 to 2018. For reasons explained in The Last Review I'll Ever Do For OJS, I won't provide additional linking information. These reviews are here as how-to examples.


Tuesday, 6 November 2018

Statistics in Politics and Demographics

In introductory statistics courses, we present these polls as if they are draws from a binomial distribution. That is, that every member of the relevant population is equally likely to be a respondent in the sample, and that they will actually respond with their actual voting intention or approval. Poll aggregating websites like Fivethirtyeight and Politifact have shown how far from the truth a real political poll can be.

This post is a draft of a proposal for a undergraduate interdisciplinary courses between statistics and political science on polling.


Wednesday, 31 October 2018

Parameter Estimation of Binned Data

Section 1: Introduction – The Problem of Binned Data


Hypothetically, say you’re given data like this in Table 1 below, and you’re asked to find the mean:

Group
Frequency
0 to 25
114
25 to 50
76
50 to 75
58
75 to 100
51
100 to 250
140
250 to 500
107
500 to 1000
77
1000 to 5000
124
5000 or more
42



Table 1: Example Binned Data.
Border cases go to the lower bin.

The immediate problem is that the mean (and the variance, and many other statistics) is the average of exact values by we have ranges of values. There are a few things similar to getting the mean that could be done: