Fictional frequency records: equal rates, a recorded zero and missing data

Select the code and use your copy shortcut. Changes in this preview are temporary.

<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><meta name="nos-demo-layout" content="responsive-lab"><title>Counts and observation windows</title><style>body{margin:0;font:17px/1.55 system-ui;color:#182f3c;background:#f5f6f8}main{max-width:800px;margin:auto;padding:24px}h1{font-size:clamp(28px,5vw,38px);line-height:1.15}h2{font-size:23px}label{display:block;font-weight:bold}select{max-width:100%;padding:10px;font:inherit}#result{background:white;border-left:6px solid #365c83;padding:18px;margin:20px 0}#result strong{display:block;font-size:25px}li{margin:10px 0}pre{white-space:pre-wrap;overflow-wrap:anywhere;background:white;padding:18px;font:16px/1.6 system-ui}aside{border-top:1px solid #728797;padding-top:16px}@media print{select{display:none}}</style></head><body><main><p>Original fictional recording exercise. No learner or classroom data.</p><h1>Keep the observed minutes beside the count</h1><p>Authored definition: count when the learner rises from their assigned chair and moves away during independent desk work; the occurrence ends on return. Agreed movement breaks are excluded in this exercise.</p><label for="session">Review a supplied session</label><select id="session"><option value="A">A: 3 occurrences / 10 minutes</option><option value="B">B: 6 occurrences / 20 minutes</option><option value="C">C: 0 occurrences / 10 minutes</option><option value="D">D: count and duration not supplied</option></select><div id="result" aria-live="polite"></div><h2>Read the comparison</h2><ul><li>A: 3 ÷ 10 = 0.3 occurrences per minute.</li><li>B: 6 ÷ 20 = 0.3 occurrences per minute.</li><li>C: 0 ÷ 10 = 0 occurrences per minute for that recorded window.</li><li>D: missing count and duration; no rate can be calculated.</li></ul><p>A and B have equal rates despite different totals. No cause, improvement, diagnosis or intervention result is supplied.</p><h2>Blank observation record</h2><pre>Record / permitted learner reference: __________
Definition and exclusions: __________
Setting / observer / date: __________
Actual start and end / observed duration and unit: __________
Occurrence tally and total: __________
Rate with count, duration and unit: __________
Interrupted or unobserved time: __________
Source record / review questions: __________</pre><aside>This page only compares supplied fictional records. It does not collect, save or send classroom observations.</aside></main><script>const records={A:{count:3,minutes:10},B:{count:6,minutes:20},C:{count:0,minutes:10},D:{count:null,minutes:null}};function draw(){const id=document.querySelector('#session').value,r=records[id],valid=Number.isFinite(r.count)&&Number.isFinite(r.minutes)&&r.count>=0&&r.minutes>0;window.review={id,...r,rate:valid?r.count/r.minutes:null};const box=document.querySelector('#result');box.replaceChildren();const strong=document.createElement('strong');strong.textContent=valid?window.review.rate+' occurrences per minute':'Not calculated';box.append(strong,document.createTextNode(valid?'Session '+id+': '+r.count+' occurrences during '+r.minutes+' observed minutes.':'Session D: count and observed duration are not supplied. Missing is not zero.'));}document.querySelector('#session').addEventListener('change',draw);draw();</script></body></html>