// Numbas version: exam_results_page_options
{"name": "Use data uploaded by the student", "extensions": ["stats"], "custom_part_types": [], "resources": [["question-resources/Data.csv", "/srv/numbas/media/question-resources/Data.csv"]], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"type": "question", "variables": {}, "variable_groups": [], "name": "Use data uploaded by the student", "metadata": {"licence": "Creative Commons Attribution 4.0 International", "description": "<p>Get the student to upload their experimental data in a CSV file, then ask them to compute statistics on it.</p>"}, "variablesTest": {"maxRuns": 100, "condition": ""}, "parts": [{"showFeedbackIcon": true, "type": "information", "scripts": {}, "variableReplacementStrategy": "originalfirst", "variableReplacements": [], "showCorrectAnswer": true, "prompt": "<div data-bind=\"with: question.display\">\n<p><input id=\"file\" type=\"file\"/></p>\n<div id=\"output\" data-bind=\"visible: gotData\">\n<p>Your data</p>\n<div id=\"data-table\">\n<table>\n<thead>\n<tr>\n<th>Weight (N)</th>\n<th>Length (cm)</th>\n</tr>\n</thead>\n<tbody data-bind=\"foreach: data\">\n<tr>\n<td data-bind=\"text: $data[0]\"></td>\n<td data-bind=\"text: $data[1]\"></td>\n</tr>\n</tbody>\n</table>\n</div>\n<div data-bind=\"with: question.stats, typeset: question.stats\">\n<p>$n$: <span data-bind=\"text: n\"></span></p>\n<p>$\\sum x$: <span data-bind=\"text: sx\"></span></p>\n<p>$\\sum y$: <span data-bind=\"text: sy\"></span></p>\n<p>$\\sum x^2$: <span data-bind=\"text: sxx\"></span></p>\n<p>$\\sum y^2$: <span data-bind=\"text: syy\"></span></p>\n<p>$\\sum xy$: <span data-bind=\"text: sxy\"></span></p>\n<p>$\\alpha$: <span data-bind=\"text: Numbas.math.niceNumber(alpha,{precisionType: 'dp', precision:3})\"></span></p>\n<p>$\\beta$: <span data-bind=\"text: Numbas.math.niceNumber(beta,{precisionType: 'dp', precision:3})\"></span></p>\n</div>\n</div>\n</div>", "marks": 0}, {"showFeedbackIcon": true, "type": "gapfill", "scripts": {}, "variableReplacementStrategy": "originalfirst", "variableReplacements": [], "showCorrectAnswer": true, "gaps": [{"variableReplacements": [], "scripts": {"mark": {"script": "// get the computed stats\nvar stats = this.question.stats();\n// set the correct answer to the computed stat\nthis.settings.minvalue = stats.sx;\nthis.settings.maxvalue = stats.sx;", "order": "before"}}, "variableReplacementStrategy": "originalfirst", "mustBeReducedPC": 0, "showCorrectAnswer": true, "type": "numberentry", "mustBeReduced": false, "maxValue": "0", "showFeedbackIcon": true, "correctAnswerStyle": "plain", "allowFractions": false, "notationStyles": ["plain", "en", "si-en"], "minValue": "0", "correctAnswerFraction": false, "marks": 1}, {"variableReplacements": [], "scripts": {"mark": {"script": "var stats = this.question.stats();\nthis.settings.minvalue = stats.sy;\nthis.settings.maxvalue = stats.sy;", "order": "before"}}, "variableReplacementStrategy": "originalfirst", "mustBeReducedPC": 0, "showCorrectAnswer": true, "type": "numberentry", "mustBeReduced": false, "maxValue": "0", "showFeedbackIcon": true, "correctAnswerStyle": "plain", "allowFractions": false, "notationStyles": ["plain", "en", "si-en"], "minValue": "0", "correctAnswerFraction": false, "marks": 1}, {"variableReplacements": [], "scripts": {"mark": {"script": "var stats = this.question.stats();\nthis.settings.minvalue = stats.sxx;\nthis.settings.maxvalue = stats.sxx;", "order": "before"}}, "variableReplacementStrategy": "originalfirst", "mustBeReducedPC": 0, "showCorrectAnswer": true, "type": "numberentry", "mustBeReduced": false, "maxValue": "0", "showFeedbackIcon": true, "correctAnswerStyle": "plain", "allowFractions": false, "notationStyles": ["plain", "en", "si-en"], "minValue": "0", "correctAnswerFraction": false, "marks": 1}, {"variableReplacements": [], "scripts": {"mark": {"script": "var stats = this.question.stats();\nthis.settings.minvalue = stats.syy;\nthis.settings.maxvalue = stats.syy;", "order": "before"}}, "variableReplacementStrategy": "originalfirst", "mustBeReducedPC": 0, "showCorrectAnswer": true, "type": "numberentry", "mustBeReduced": false, "maxValue": "0", "showFeedbackIcon": true, "correctAnswerStyle": "plain", "allowFractions": false, "notationStyles": ["plain", "en", "si-en"], "minValue": "0", "correctAnswerFraction": false, "marks": 1}, {"variableReplacements": [], "scripts": {"mark": {"script": "var stats = this.question.stats();\nthis.settings.minvalue = stats.sxy;\nthis.settings.maxvalue = stats.sxy;", "order": "before"}}, "variableReplacementStrategy": "originalfirst", "mustBeReducedPC": 0, "showCorrectAnswer": true, "type": "numberentry", "mustBeReduced": false, "maxValue": "0", "showFeedbackIcon": true, "correctAnswerStyle": "plain", "allowFractions": false, "notationStyles": ["plain", "en", "si-en"], "minValue": "0", "correctAnswerFraction": false, "marks": 1}], "prompt": "<p>Compute the following statistics from your data.</p>\n<table>\n  <thead>\n    <tr>\n      <th>$\\sum x$</th>\n      <th>$\\sum y$</th>\n      <th>$\\sum x^2$</th>\n      <th>$\\sum y^2$</th>\n      <th>$\\sum xy$</th>\n    </tr>\n  </thead>\n  <tbody>\n    <tr>\n      <td>[[0]]</td>\n      <td>[[1]]</td>\n      <td>[[2]]</td>\n      <td>[[3]]</td>\n      <td>[[4]]</td>\n    </tr>\n  </tbody>\n</table>", "marks": 0}], "functions": {}, "tags": ["csv", "demo", "experiment", "statistics"], "extensions": ["stats"], "preamble": {"css": "#data-table {\n  max-height: 30em;\n  overflow-y: auto;\n  display: inline-block;\n}\na, a:hover {\n  color: blue;\n}\na:hover {\n  text-decoration: underline;\n}", "js": "// read a csv file\nfunction readCSV(text) {\n  var lines = text.split('\\n');\n  return lines.map(function(line){return line.split(',')});\n}\n\n// wait until the question has been generated\nquestion.signals.on('HTMLAttached',function(e) {\n  var display = question.display;\n\n  // set up an observable for the data array\n  var _data = display.data = ko.observableArray([]);\n  \n  // has the student uploaded data?\n  display.gotData = ko.computed(function() {\n    return _data().length>0;\n  });\n  \n  // an observable object containing various computed statistics about the data - updates automatically when the data changes\n  var stats = question.stats = ko.computed(function() {\n    var data = _data();\n    \n    // weights are in the first column\n    var weights = data.map(function(r){return r[0]});\n    // lengths in the second column\n    var lengths = data.map(function(r){return r[1]});\n    \n    // how many samples?\n    var n = data.length;\n    \n    // components of the linear regression calculation\n    var sx = jStat.sum(weights);\n    var sy = jStat.sum(lengths);\n    var sxx = jStat.sum(weights.map(function(x){return x*x}));\n    var syy = jStat.sum(lengths.map(function(x){return x*x}));\n    var sxy = jStat.sum(data.map(function(r){ return r[0]*r[1]}));\n    \n    // coefficients of the linear regression model\n    var beta = (sxy - (sx*sy)/n)/(sxx-(sx*sx)/n);\n    var alpha = (sy-beta*sx)/n;\n    \n    var stats = {\n      sx: sx,\n      sy: sy,\n      sxx: sxx,\n      syy: syy,\n      sxy: sxy,\n      alpha: alpha,\n      beta: beta,\n      n: data.length\n    };\n    \n    return stats;\n  });\n  \n  // format a number to 3 d.p.\n  function niceNumber(n) {\n    return Numbas.math.niceNumber(n,{precisionType: 'dp', precision: 3});\n  }\n  \n  // code to read the file when it's uploaded\n  $('#file').on('change',function(e) {\n    var f = e.target.files[0];\n    var reader = new FileReader();\n    reader.onload = function(e) {\n      var data = readCSV(e.target.result);\n      _data(data.map(function(row){ return row.map(parseFloat)}).filter(function(row){return !isNaN(row[0])}));\n    }\n    reader.readAsText(f);\n  });\n});"}, "ungrouped_variables": [], "statement": "<p><strong>This question will only work in browsers that support the HTML5 File API! For Internet Explorer users, that means version 10 onwards.</strong></p>\n<p>How does the length of a spring change when you suspend different masses from it? Make measurements of your spring's length when hanging various different weights from it.</p>\n<p>Download <a href=\"resources/question-resources/Data.csv\">the data spreadsheet</a> and open it in a program such as <em>Microsoft Excel</em>. Enter your data, save the file, and then upload it using the button below.</p>", "advice": "", "rulesets": {}, "contributors": [{"name": "Christian Lawson-Perfect", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7/"}]}]}], "contributors": [{"name": "Christian Lawson-Perfect", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7/"}]}