31:T431,table = { const root = document.createElement('table'); root.appendChild( html` assuming a normal distribution… Age range (years) Number of subjects Mean LogMAR ± standard deviation ${ Math.round( percentOfPeople * 100 ) }% of people have a LogMAR score worse than ${ Math.round( percentOfPeople * 100 ) }% of people can’t discern DPR ≥ `); buckets.forEach( ( bucket ) => { const quantile = stdlib.base.dists.normal.quantile( 1 - percentOfPeople, bucket.meanLogMAR, bucket.standardDeviation ); const maxDPRforPercent = logMAR2dpr( quantile ); root.appendChild( html` ${ bucket.ageRange } ${ bucket.numberOfSubjects } ${ bucket.meanLogMAR } ± ${ bucket.standardDeviation } ${ Math.round( quantile * 100 ) / 100 } ${ Math.round( maxDPRforPercent * 100 ) / 100 } ` ); } ) return root } 32:T531, buckets = [ { ageRange: '18-24', numberOfSubjects: 37, meanLogMAR: -0.13, standardDeviation: 0.06 }, { ageRange: '25–29', numberOfSubjects: 14, meanLogMAR: -0.16, standardDeviation: 0.06 }, { ageRange: '30-34', numberOfSubjects: 13, meanLogMAR: -0.15, standardDeviation: 0.06 }, { ageRange: '35–39', numberOfSubjects: 13, meanLogMAR: -0.14, standardDeviation: 0.07 }, { ageRange: '40-44', numberOfSubjects: 21, meanLogMAR: -0.13, standardDeviation: 0.05 }, { ageRange: '45–49', numberOfSubjects: 19, meanLogMAR: -0.12, standardDeviation: 0.05 }, { ageRange: '50-54', numberOfSubjects: 17, meanLogMAR: -0.10, standardDeviation: 0.06 }, { ageRange: '55–59', numberOfSubjects: 14, meanLogMAR: -0.10, standardDeviation: 0.04 }, { ageRange: '60-64', numberOfSubjects: 14, meanLogMAR: -0.07, standardDeviation: 0.06 }, { ageRange: '65–69', numberOfSubjects: 18, meanLogMAR: -0.05, standardDeviation: 0.05 }, { ageRange: '70-74', numberOfSubjects: 23, meanLogMAR: -0.04, standardDeviation: 0.04 }, { ageRange: '75+', numberOfSubjects: 20, meanLogMAR: -0.02, standardDeviation: 0.05 } ]33:[] 2f:{"title":"Visual acuity, age, and DPR","cells":[{"id":0,"value":"md`# Visual acuity, age, and DPR`","pinned":false,"hidden":false,"mode":"ojs"},{"id":185,"value":"md`For this to make any sense you should probably read my first foray into the question, [“how many DPRs is too many DPRs? How many DPRs is enough?”](https://observablehq.com/@eeeps/visual-acuity-and-device-pixel-ratio)\n\nAlso, take a minute to [see how many DPRs is enough for you, on your current device](https://observablehq.com/@eeeps/comparing-dprs).\n\nOkay, read on...\n`\n\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":124,"value":"md`## Assumptions\n\n1. [\\`1 px\\`, in CSS = a visual angle of 0.0213°](https://drafts.csswg.org/css-values-3/#reference-pixel) (this, in turn, relies on assumptions about viewing distance and how browsers choose \\`window.devicePixelRatio\\`)\n2. A [normal distribution](https://en.wikipedia.org/wiki/Normal_distribution) of visual acuity amongst humans. This [might be a shaky assumption](https://eric-cloudinary-res.cloudinary.com/image/upload/v1552942657/visual-acuity-distribution.png).\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":143,"value":"md`## Calculations`","pinned":false,"hidden":false,"mode":"ojs"},{"id":41,"value":"viewof percentOfPeople = { \n const form = html``;\n const input = form.querySelector('input'),\n output = form.querySelector('output');\n function update() {\n output.textContent = `${ Math.round( input.value * 100 ) }%`;\n form.value = input.value;\n }\n input.addEventListener( 'input', update );\n update();\n return form;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":26,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":155,"value":"md`## References`","pinned":false,"hidden":false,"mode":"ojs"},{"id":166,"value":"md`### Elliott et al. (1995)\n\nElliott, David & C. H. Yang, Kathy & Whitaker, David. (1995). Visual Acuity Changes Throughout Adulthood in Normal, Healthy Eyes: Seeing Beyond 6/6. Optometry and vision science : official publication of the American Academy of Optometry. 72. 186-91. 10.1097/00006324-199503000-00006.\n\n[\\[PubMed\\]](https://www.ncbi.nlm.nih.gov/pubmed/7609941)\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":150,"value":"html`

Table from Elliott et al that I took the distributional data from

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":159,"value":"html`

Chart of all datapoints from Elliott et al.

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":170,"value":"md`### Ohlsson & Villarreal (2005)\n\nOhlsson, J. and Villarreal, G. (2005), Normal visual acuity in 17–18 year olds. Acta Ophthalmologica Scandinavica, 83: 487-491. doi:[10.1111/j.1600-0420.2005.00516.x](https://doi.org/10.1111/j.1600-0420.2005.00516.x)\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":177,"value":"html`

Chart of all datapoints from Ohlsson & Villarreal. Note that the subjects were all 17-18 year olds.

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":183,"value":"html`

Chart in which Ohlsson & Villarreal compare their study’s mean visual acuities to other visual acuity studies’ means (including Elliott et al.’s)

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2,"value":"stdlib = require( \"https://unpkg.com/@stdlib/stdlib@0.0.60/dist/stdlib-flat.min.js\" )","pinned":false,"hidden":false,"mode":"ojs"},{"id":59,"value":"$32","pinned":false,"hidden":false,"mode":"ojs"},{"id":76,"value":"degreesMinutesSeconds2Decimal = function(degrees, minutes, seconds) {\n return degrees + ( minutes / 60 ) + ( seconds / ( 60 * 60 ) );\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":74,"value":"logMAR2Decimal = function( logMar ) {\n const minutes = 10 ** ( logMar );\n return degreesMinutesSeconds2Decimal(0, minutes, 0);\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":78,"value":"cssPx = 0.0213 // degrees","pinned":false,"hidden":false,"mode":"ojs"},{"id":80,"value":"logMAR2dpr = function( logMAR ) { \n return cssPx / logMAR2Decimal( logMAR )\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":101,"value":"style = html``","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W33","stdlib":"1","titling":"auto"}