The Natural Increase Rate (NIR) is a fundamental demographic indicator that measures the growth or decline of a population solely due to the difference between births and deaths. It excludes migration, making it a pure measure of how a population changes based on its own reproductive and mortality patterns. A positive NIR indicates population growth, while a negative NIR signifies population decline. Understanding the NIR is crucial for demographic analysis, population projections, and formulating effective public health and social policies.
function calculateNIR() {
var birthRateInput = document.getElementById("birthRate");
var deathRateInput = document.getElementById("deathRate");
var resultDiv = document.getElementById("result");
var birthRate = parseFloat(birthRateInput.value);
var deathRate = parseFloat(deathRateInput.value);
if (isNaN(birthRate) || isNaN(deathRate)) {
resultDiv.innerHTML = "Please enter valid numbers for both birth rate and death rate.";
return;
}
// Formula for Natural Increase Rate: (Crude Birth Rate – Crude Death Rate)
var nir = birthRate – deathRate;
resultDiv.innerHTML = "The Natural Increase Rate is: " + nir.toFixed(2) + " per 1,000 people.";
if (nir > 0) {
resultDiv.innerHTML += "This indicates a population increase.";
} else if (nir < 0) {
resultDiv.innerHTML += "This indicates a population decrease.";
} else {
resultDiv.innerHTML += "This indicates a stable population (no natural change).";
}
}
.calculator-container {
font-family: sans-serif;
border: 1px solid #ccc;
padding: 20px;
border-radius: 8px;
max-width: 500px;
margin: 20px auto;
background-color: #f9f9f9;
}
.calculator-container h2 {
text-align: center;
margin-bottom: 20px;
color: #333;
}
.calculator-inputs {
margin-bottom: 20px;
}
.input-row {
margin-bottom: 15px;
display: flex;
align-items: center;
justify-content: space-between;
}
.input-row label {
flex: 1;
margin-right: 10px;
color: #555;
}
.input-row input {
flex: 1;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
box-sizing: border-box;
}
.calculator-container button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #007bff;
color: white;
border: none;
border-radius: 4px;
font-size: 16px;
cursor: pointer;
transition: background-color 0.3s ease;
}
.calculator-container button:hover {
background-color: #0056b3;
}
.calculator-result {
margin-top: 20px;
padding: 15px;
background-color: #e9ecef;
border: 1px solid #ced4da;
border-radius: 4px;
text-align: center;
color: #333;
}
.calculator-result p {
margin: 5px 0;
}