JavaScript Program for Inverse t Distribution Calculator

Last Updated : 28 Sep, 2023

In this article, we will discuss the Inverse t Distribution Calculator using JavaScript. An inverse t-distribution calculator is a valuable tool for calculating critical values from the t-distribution. It helps researchers and analysts in hypothesis testing, confidence interval estimation, and other statistical calculations.

Using jStat library

In this approach, we are using jStat library which has built-in functions.
We are creating a function that takes input of probability and degree of freedom from the form of HTML.
We are using ‘jStat.studentt.inv’ function for calculating the inverse t distribution.

Example: This example shows the use of the above-explained approach.

HTML

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8"> 
    <meta name="viewport" 
          content="width=device-width, initial-scale=1.0"> 
    <title>Inverse t-Distribution Calculator</title> 
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/jstat/1.7.1/jstat.min.js"> 
      </script>    
</head> 
<body> 
    <h1>Inverse t-Distribution Calculator</h1> 
  
    <form> 
        <label for="prob">Probability (p):</label> 
        <input type="number" id="prob" step="0.01" 
               min="0" max="1" required> 
        <br> 
        <label for="dof">Degrees of Freedom (DOF):</label> 
        <input type="number" id="dof" required> 
        <br> 
        <button type="button" onclick="inverseT()"> 
              Calculate 
          </button> 
    </form> 
  
    <div id="result"></div> 
  
    <script> 
        function fun(p, DOF) { 
            if (p < 0 || p > 1) { 
                return  
                  "Probability value (p) must be between 0 and 1."; 
            } 
  
            const result = jStat.studentt.inv(p, DOF); 
            return result; 
        } 
  
        function inverseT() { 
            const probInput =  
                  document.getElementById("prob"); 
            const DOF =  
                  document.getElementById("dof"); 
            const ans =  
                  document.getElementById("result"); 
  
            const prob = parseFloat(probInput.value); 
            const dof = parseInt(DOF.value); 
  
            const inverseT = fun(prob, dof); 
  
            if (typeof inverseT ===  
                'number' && !isNaN(inverseT)) { 
                ans.textContent =  
                  `Inverse t-distribution for p=${prob} and DOF=${dof}: ${inverseT}`; 
            } else { 
                ans.textContent = inverseT; 
            } 
        } 
    </script> 
</body> 
  
</html>

CSS

body { 
    font-family: Arial, sans-serif; 
    text-align: center; 
} 
  
h1 { 
    color: #333; 
} 
  
form { 
    margin: 20px auto; 
    padding: 20px; 
    border: 1px solid #ccc; 
    width: 300px; 
    background-color: #f7f7f7; 
} 
  
label { 
    display: block; 
    margin-bottom: 10px; 
} 
  
input[type="number"] { 
    width: 100%; 
    padding: 5px; 
    margin-bottom: 10px; 
} 
  
button { 
    background-color: #4CAF50; 
    color: white; 
    border: none; 
    padding: 10px 20px; 
    cursor: pointer; 
} 
  
button:hover { 
    background-color: #45a049; 
} 
  
#result { 
    margin-top: 20px; 
    font-weight: bold; 
    padding: 10px; 
    border: 1px solid #ccc; 
    background-color: #f0f0f0; 
    color: #4CAF50; 
}