IQ Distribution Master

<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
        font: 10px sans-serif;
    }
    .axis path,
    .axis line {
        fill: none;
        stroke: #000;
        shape-rendering: crispEdges;
    }
    .line {
        fill: none;
        stroke: steelblue;
        stroke-width: 1.5px;
    }
    
    .area {
      fill: red; 
    }
    
    .label {
      fill: red;
    }
</style>
<label>Mean: </label><input id='mean' type='range' min='70' max='130' value='100'><span id='mean-output'>100</span>
<br />
<label>Spread: </label><input id='sd' type='range' min='10' max='30' value='15'><span id='sd-output'>15</span>
<br/>
<svg></svg>

//setting up empty data array
var data = [];
var dataBelowCutoff = [];
var cutoffCdf = 0;

getData(); // popuate data

// line chart based on https://bl.ocks.org/mbostock/3883245
var margin = {
        top: 20,
        right: 20,
        bottom: 30,
        left: 50
    },
    width = 960 - margin.left - margin.right,
    height = 400 - margin.top - margin.bottom;

var x = d3.scaleLinear()
    .range([0, width]);

var y = d3.scaleLinear()
    .range([height, 0]);

var xAxis = d3.axisBottom()
    .scale(x);

var yAxis = d3.axisLeft()
    .scale(y);

var line = d3.line()
    .x(function(d) {
        return x(d.q);
    })
    .y(function(d) {
        return y(d.p);
    });
var svg = d3.select("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
    .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

x.domain([40, 160]);
y.domain(d3.extent(data, function(d) {
    return d.p;
}));

svg.append("g")
    .attr("class", "x axis")
    .attr("transform", "translate(0," + height + ")")
    .call(xAxis);

svg.append("g")
    .attr("class", "y axis")
    .call(yAxis);
    
var path = svg.append("path")
    .datum(data)
    .attr("class", "line")
    .attr("d", line);

var area = d3.area()
	.x(function(d) {
  	return x(d.q);
  })
  .y(function(d) {
  	return y(d.p);
  })
  .y1(y(0));
  
var areaPath = svg.append('path')
	.attr('class', 'area');

var textLabel = svg.append('text')
	.attr('class', 'label')
  .attr('x', x(70));
  
update();
  
function update() {
  path.datum(data).attr("d", line);
  areaPath.datum(dataBelowCutoff).attr("d", area);
  textLabel
  	.attr('y', y(dataBelowCutoff[dataBelowCutoff.length - 1].p / 2))
  	.text(d3.format(".1%")(cutoffCdf));
    
  document.getElementById('mean-output').innerHTML = document.getElementById('mean').value;
  document.getElementById('sd-output').innerHTML = document.getElementById('sd').value;
}

d3.select('#mean').on('input', function() {
	getData();
  update();
});

d3.select('#sd').on('input', function() {
	getData();
  update();
})

function getData() {
  var mean = parseFloat(document.getElementById('mean').value);
  var sd = parseFloat(document.getElementById('sd').value);
  data = [];
  // loop to populate data array with 
  // probabily - quantile pairs
  for (var i = 40; i < 160; i += 1) {
      q = i
      p = jStat.normal.pdf(i, mean, sd);
      el = {
          "q": q,
          "p": p
      }
      
      data.push(el);
  };

dataBelowCutoff = data.slice(0, 30);
  cutoffCdf = jStat.normal.cdf(70, mean, sd);
}
</script>

https://d3js.org/d3.v4.min.js

https://cdn.jsdelivr.net/jstat/latest/jstat.min.js