.epidemiology-calc-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
line-height: 1.6;
}
.mr-calculator-box {
background: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
.mr-input-group {
margin-bottom: 20px;
}
.mr-input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #2c3e50;
}
.mr-input-group input, .mr-input-group select {
width: 100%;
padding: 12px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.mr-input-group input:focus, .mr-input-group select:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 0 3px rgba(0,123,255,0.25);
}
.mr-btn {
background-color: #0056b3;
color: white;
border: none;
padding: 14px 24px;
font-size: 18px;
font-weight: 600;
border-radius: 4px;
cursor: pointer;
width: 100%;
transition: background-color 0.2s;
}
.mr-btn:hover {
background-color: #004494;
}
#mr_result_container {
margin-top: 25px;
padding: 20px;
background-color: #d4edda;
border: 1px solid #c3e6cb;
border-radius: 4px;
display: none;
}
.mr-result-value {
font-size: 28px;
font-weight: 700;
color: #155724;
margin-bottom: 5px;
}
.mr-result-label {
font-size: 14px;
color: #155724;
}
.mr-error {
color: #721c24;
background-color: #f8d7da;
border: 1px solid #f5c6cb;
padding: 10px;
border-radius: 4px;
margin-top: 15px;
display: none;
}
.mr-content h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
.mr-content p {
margin-bottom: 15px;
}
.mr-formula-box {
background: #eef2f5;
padding: 15px;
border-left: 4px solid #0056b3;
font-family: monospace;
margin: 20px 0;
}
function calculateMortalityRate() {
var deathsInput = document.getElementById('mr_deaths');
var populationInput = document.getElementById('mr_population');
var multiplierInput = document.getElementById('mr_multiplier');
var resultContainer = document.getElementById('mr_result_container');
var errorContainer = document.getElementById('mr_error');
var finalRateDisplay = document.getElementById('mr_final_rate');
var interpretationDisplay = document.getElementById('mr_interpretation');
// Reset display
resultContainer.style.display = 'none';
errorContainer.style.display = 'none';
var deaths = parseFloat(deathsInput.value);
var population = parseFloat(populationInput.value);
var multiplier = parseFloat(multiplierInput.value);
// Validation logic
if (isNaN(deaths) || isNaN(population)) {
errorContainer.innerText = "Please enter valid numbers for both deaths and population.";
errorContainer.style.display = 'block';
return;
}
if (deaths < 0 || population 0.";
errorContainer.style.display = 'block';
return;
}
if (deaths > population) {
errorContainer.innerText = "Note: Number of deaths exceeds total population. Please verify your data.";
errorContainer.style.display = 'block';
// We do not return here, we allow the calculation but warn the user.
}
// Core Calculation
var rawRate = (deaths / population) * multiplier;
// Formatting output
// If the number is very small, show more decimals. If large, show fewer.
var formattedRate;
if (rawRate < 0.01) {
formattedRate = rawRate.toPrecision(4);
} else {
formattedRate = rawRate.toFixed(2);
}
// Generate interpretation text based on multiplier
var unitText = "";
if (multiplier === 100) unitText = "% (Case Fatality Rate / Percentage)";
else if (multiplier === 1000) unitText = "per 1,000 people";
else if (multiplier === 10000) unitText = "per 10,000 people";
else if (multiplier === 100000) unitText = "per 100,000 people";
finalRateDisplay.innerText = formattedRate;
interpretationDisplay.innerText = "Deaths " + unitText;
resultContainer.style.display = 'block';
}
Understanding Mortality Rate Calculations in Epidemiology
In epidemiology, mortality rates are fundamental measures of disease frequency. They quantify the occurrence of death in a defined population during a specified interval. This calculator helps researchers, students, and public health professionals compute various types of mortality rates, including Crude Mortality Rate, Cause-Specific Mortality Rate, and Case Fatality Rate (CFR).
The Formula
The general formula for calculating a mortality rate is:
Mortality Rate = (Number of Deaths / Population at Risk) × Multiplier
Where:
- Numerator: The number of deaths that occurred during the specific time period.
- Denominator: The size of the population from which the deaths occurred (often the mid-year population).
- Multiplier (10n): A scaling factor (e.g., 1,000 or 100,000) used to make the result easier to read and compare.
Types of Mortality Rates
Depending on the inputs used, this calculator can derive several key epidemiological metrics:
1. Crude Mortality Rate (CDR)
This is the total number of deaths from all causes per 1,000 population. It measures the absolute risk of dying in a population but does not account for age or specific causes.
2. Cause-Specific Mortality Rate
This measures deaths from a specific cause (e.g., lung cancer or influenza) relative to the total population. Because these numbers are often smaller, they are typically expressed per 100,000 population.
3. Case Fatality Rate (CFR)
Often used during outbreaks, the CFR measures the severity of a disease. It is the proportion of people diagnosed with a specific disease who die from it. To calculate CFR, enter the number of deaths as the numerator and the number of diagnosed cases as the denominator. Select "Per 100" to get a percentage.
Example Calculation
Suppose a city has a population of 500,000. In one year, there were 4,500 total deaths.
- Input Deaths: 4500
- Input Population: 500000
- Multiplier: Per 1,000
- Calculation: (4,500 ÷ 500,000) × 1,000 = 9.0
The Crude Mortality Rate is 9 deaths per 1,000 population.
Why the Multiplier Matters
In epidemiology, raw fractions like 0.00005 are difficult to interpret. By multiplying by a power of 10 (the base), we convert these fractions into whole numbers that are easier to communicate.
Standard Conventions:
- Per 100 (%): Used for Case Fatality Rates and Proportionate Mortality.
- Per 1,000: Used for Crude Death Rates and Infant Mortality Rates.
- Per 100,000: Used for Cause-Specific Mortality (e.g., cancer rates) and Maternal Mortality Ratios.