Incidence Rate Calculator
This calculator helps you determine the incidence rate of a specific event or disease within a defined population over a specific period. The incidence rate is a measure of how quickly new cases of a disease or event occur in a population at risk.
function calculateIncidenceRate() {
var newCasesInput = document.getElementById("newCases");
var populationAtRiskInput = document.getElementById("populationAtRisk");
var timePeriodInput = document.getElementById("timePeriod");
var resultDiv = document.getElementById("result");
var newCases = parseFloat(newCasesInput.value);
var populationAtRisk = parseFloat(populationAtRiskInput.value);
var timePeriod = parseFloat(timePeriodInput.value);
if (isNaN(newCases) || isNaN(populationAtRisk) || isNaN(timePeriod)) {
resultDiv.innerHTML = "Please enter valid numbers for all fields.";
return;
}
if (populationAtRisk <= 0) {
resultDiv.innerHTML = "Population at risk must be greater than zero.";
return;
}
if (timePeriod <= 0) {
resultDiv.innerHTML = "Time period must be greater than zero.";
return;
}
// Formula for Incidence Rate: (Number of New Cases / Population at Risk) * (1 / Time Period)
// Often expressed per a specific number of individuals (e.g., per 1000 or 100,000)
// We will calculate the rate per person per year initially, and then provide common multipliers.
var incidenceRatePerPerson = (newCases / populationAtRisk) / timePeriod;
var incidenceRatePer1000 = incidenceRatePerPerson * 1000;
var incidenceRatePer100000 = incidenceRatePerPerson * 100000;
var htmlOutput = "
Results:
";
htmlOutput += "The incidence rate is:
" + incidenceRatePerPerson.toFixed(6) + " per person per year.";
htmlOutput += "This is equivalent to:
" + incidenceRatePer1000.toFixed(2) + " new cases per 1,000 people per year.";
htmlOutput += "Or:
" + incidenceRatePer100000.toFixed(2) + " new cases per 100,000 people per year.";
resultDiv.innerHTML = htmlOutput;
}
#incidence-rate-calculator {
font-family: sans-serif;
border: 1px solid #ddd;
padding: 20px;
border-radius: 8px;
max-width: 500px;
margin: 20px auto;
background-color: #f9f9f9;
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
}
.form-group input[type="number"] {
width: calc(100% – 12px);
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
}
#incidence-rate-calculator button {
background-color: #4CAF50;
color: white;
padding: 10px 15px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 16px;
margin-top: 10px;
}
#incidence-rate-calculator button:hover {
background-color: #45a049;
}
.calculator-result {
margin-top: 20px;
padding: 15px;
border: 1px solid #e0e0e0;
border-radius: 4px;
background-color: #fff;
}
.calculator-result h3 {
margin-top: 0;
color: #333;
}