33:T5bc,md`# Coronavirus logistic isopleths This builds on a previous [recreation](https://observablehq.com/@tophtucker/recreating-john-burn-murdochs-coronavirus-tracker) of [John Burn-Murdoch](https://twitter.com/jburnmurdoch)’s daily coronavirus tracker [at the FT](https://www.ft.com/coronavirus-latest), using [data](https://observablehq.com/@tophtucker/covid-tracking-project-data) from [The COVID Tracking Project](https://covidtracking.com/). It overlays the derivatives of various [logistic curves](https://en.wikipedia.org/wiki/Logistic_function#Derivative) on plots of new daily cases. John’s charts often include lines representing various doubling rates, which helps interpret the slopes of the paths of different regions. The idea here is to give _some_ idea of what the areas under these lines may be, as the areas will represent the total cumulative number of cases. Every curve of the same color covers the same area, though some are flatter than others. (This representation does not really address or highlight the idea that a flatter version of the same number of cases tends to lead to better outcomes.) My main takeaway is that these paths do not fit logistic curves very well. See also John D. Cook recently on [Exponential growth vs logistic growth](https://www.johndcook.com/blog/2020/04/09/exponential-logistic-growth/). See also tweet for [video of how it looked at the time](https://twitter.com/tophtucker/status/1251102546577559553). ---`34:Ta0b,chart = { replay; const node = html`${style} `; d3.select(node) .select(".curves") .selectAll("g") .transition() .delay((_, i) => i * 100) .attr("opacity", 1) .transition() .attr("opacity", .2); return node; }35:[] 31:{"title":"Coronavirus logistic isopleths","cells":[{"id":0,"value":"$33","pinned":false,"hidden":false,"mode":"ojs"},{"id":1540,"value":"viewof highlights = checkbox({\n title: \"Highlights\",\n description: \"Make these states bright.\",\n options: keys,\n value: [\"CA\", \"WA\", \"NY\", \"MA\", \"NJ\"]\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":301,"value":"viewof threshold = slider({\n min: 1,\n max: 100,\n step: 1,\n value: 10,\n title: \"Threshold\",\n description: \"Align series to show days since this threshold.\"\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":1544,"value":"viewof linOrLog = radio({\n options: [\"linear\", \"log\"],\n value: 'linear'\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":1372,"value":"viewof replay = html`