# Sensitivity and Specificity Calculator

**Created By :** Vaibhavi Kumari

**Reviewed By :** Rajashekhar Valipishetty

**Last Updated :** Apr 03, 2023

Taking help of the handy and easy to use Sensitivity and Specificity Calculator available here you can compute the necessary data needed for medical research and test evaluation. You can find PPV, NPV, the positive and negative likelihood ratio and the accuracy using this online tool. You just need to input the data as needed and click on the calculate button to avail the corresponding output.

### Sensitivity and Specificity - Definitions

**Sensitivity:** It is the proportion of people who tested positive for the disease compared to the number of all people with disease irrespective of their test result.

**Specificity:** It is the proportion of healthy people who tested negative compared to total number of people not having disease irrespective of their test result.

### How to Calculate Sensitivity and Specificity ?

In order to determine the sensitivity we use the formula **Sensitivity = TP / (TP + FN)**

To calculate the specificity we use the equation **Specificity = TN / (FP + TN)**

TP + FN = Total number of people with the disease; and TN + FP = Total number of people without the disease.

Understand the difficult concepts too easily taking the help of the online tools available at Probabilitycalculator.guru and clarify your doubts during homework or assignments.

### How do you find Positive Predictive Value and Negative Predictive Value?

In the below sections we will explain how do you calculate the positive predictive value and negative predictive value from sensitivity and specificity.

- PPV = (Sensitivity * Prevalence)/[(Sensitivity * Prevalence) + ((1 - Specificity) * (1 - Prevalence))]
- NPV =(Specificity * (1 - Prevalence))/[((1 - Sensitivity) * Prevalence) + (Specificity * (1 - Prevalence))]

### Likelihood Ratios

Positive and Negative Likelihood Ratios are used for determing the value of a test. Both of them denote the possibility of person having disease test positive and healthy person testing negative respectively.

- Positive likelihood ratio = Sensitivity / (1 - Specificity)
- Negative likelihood ratio = (1 - Sensitivity) / Specificity

### Accuracy Test

Accuracy is the ratio of correct results to all results of a test. The formula to determine accuracy is given by the equation Accuracy = (TP + TN) / (TP + TN + FP + FN)

### How to use the Sensitivity and Specificity Calculator?

Follow the below mentioned guidelines and learn the functionality of sensitivity and specificity calculator. They are as follows

- Firstly, provide the required inputs like TP, FP, TN, FN as the same four pieces of information is needed to compute sensitivity, specificity, PPV, and NPV.
- Now click on the calculate button.
- The result is displayed on a new window showing the entire calculation process.

### FAQs on Sensitivity and Specificity Calculator

**1. Are Sensitivity and Specificity Inversely Related?**

Sensitivity and Specificity are inversely proportional i.e. if one increases the other decreases.

**2. What is the formula for Sensitivity?**

The formula for Sensitivity is Sensitivity = TP / (TP + FN).

**3. How do you calculate accuracy?**

Accuracy rate of a test can be calculated using the formula Accuracy = (TP + TN) / (TP + TN + FP + FN).

**4. Where do I get the sensitivity and specificity calculator for free?**

You can get the sensitivity and specificity calculator for free on probabilitycalculator.guru a reliable portal.