The Covid-19 Symptom Data Challenge (under way at the time of writing this blog post) makes available two large sets of survey data. These are provided in granular but aggregate form ie no response-level microdata, at least for this Challenge. The two ... [Read more...]

This is a quick post looking at using biterm topic modelling, a new technique for me, on the free text responses to a survey question. I’m interested in whether this type of topic modelling might be a shortcut to analysing free text, quicker than havin... [Read more...]

Caution / who should read this - although this blog post uses some data on reporting times for Covid-19 deaths in Florida, it’s not really about that issue at all. It’s a quick dip into how to model data that comes from a mixture of two or more different ... [Read more...]

For a few weeks now I’ve been publishing estimates of the time-varying effective reproduction number for Covid-19 in Victoria (and as bonuses, NSW and Australia as a whole). Reproduction number is the average number of people each infected person infec... [Read more...]

A couple of months ago my Twitter feed featured several mass-participation stern critiques laced with sneering and mockery (aka “Twitter pile-ons”) for some naive regression modelling in the form of lines of best fit through scatter plots. All of t... [Read more...]

So an article/website is doing the rounds describing some country-level observational analysis of the relationship between hydroxychloroquine usage in the early stages of Covid-19 and deaths from that disease per million population. It purports to show... [Read more...]

Visualising growth in occupations in one industry A chart is doing the rounds purporting to show the number of administrators working in health care in the USA has grown much faster than the number of physicians - more than 3,000% growth from 1970 to ... [Read more...]

This great preprint recently came out from a team of Katelyn Gostic and others. It uses simulations to test various methods of estimating the effective reproduction number . If you are following the Covid-19 pandemic from a data angle at all, you will no doubt have come across the effective reproduction ... [Read more...]

New New Zealand election forecasts I have finalised the first proper release version of my forecast for the New Zealand general election to be held on 19 September 2020. Here are the predicted probability distributions for number of seats for several ... [Read more...]

A pleasant diversion An unexpectedly pleasant diversion from the news during the COVID-19 pandemic has been the contemplation of a considerable range of data visualisations, from the truly excellent to the amusingly bad. After all, at the excellent en... [Read more...]

Amidst controversy in several (perhaps many?) countries about the timing and pace of opening up from COVID-19 control measures, one small corner of the argument today related to why Texas is seeing record numbers of new cases of COVID-19 in the days after a range of opening up measures. In ... [Read more...]

Test positivity rates and disease incidence OK, lets talk about test positivity rates ie the proportion of administered tests that conclude the subject has the disease being tested for. These are in the news, with COVID-19 test positivity being used as an informal indicator of COVID-19 incidence and the quality ... [Read more...]

Today’s blog comes with two lessons: a statistical one, and one on troubleshooting. Rubber-duck debugging Troubleshooting lesson first. The problem described below has been causing me grief for several days. I have an important and time-critical us... [Read more...]

Possibly you have seen this graphic circulating on social media. At first it doesn’t look too remarkable, but then you notice the vertical axis. Oh. The gridlines are equally spaced on the page, but sometimes the same space represents 30 people, some... [Read more...]

Italy is routinely and correctly described as particularly vulnerable to COVID-19 because of its older age profile. I set out to understand for myself how important this factor is. What would happen if the case fatality rates observed in Italy were app... [Read more...]

Preamble I was slightly reluctant to add to the deluge of charts about the COVID-19 outbreak, but on the other hand making charts is one of the ways I relax and try to understand what’s going on around me. So first, to get out of the way my only ... [Read more...]

I’ve just finished updating and deploying a webtool that helps explore data from the New Zealand Election Study. I first built a version of this a few years back with just the 2014 wave of the study; today I’ve added the data from the time of the 2... [Read more...]

Last week I wrote about the relationship between weight and height in US adults, as seen in the US Centers for Disease Control and prevention (CDC) Behavioral Risk Factor Surveillance System, an annual telephone survey of around 400,000 interviews per year. In particular, I tested the widely-circulated claim that Body Mass ... [Read more...]

BMI has an expectations management problem Body Mass Index (BMI) is an attempt to give a quick back-of-envelope answer to the question “if someone weighs W kg, is that a lot or not very much?” Clearly the answer to that question has to take into a... [Read more...]

Last week I wrote about the impact of seeding the draw in a tennis tournament. Seeding is one way to increase the chance of the top players making it to the final rounds of a single elimination tournament, leading to fairer outcomes and to a higher cha... [Read more...]