# How to do standard deviation on a calculator

Standard deviation is a statistical measure that helps in understanding the dispersion of data points from the mean value. It provides insights into how spread out the data is, which can be useful in various fields like finance, business, science, and other disciplines. In this article, we will guide you through the process of calculating standard deviation using a calculator.

**Step 1: Gather your data**

Before diving into the calculations, ensure that you have gathered all the necessary data points required for your analysis. Organize it in a manner that is easy to comprehend and work with on your calculator.

**Step 2: Determine the number of data points (N)**

Count the total number of data points you have collected, and denote it as ‘N’. This number will be used later for calculating average and standard deviation.

**Step 3: Calculate the mean**

To calculate the mean (average) for your dataset, follow these steps:

1. Add up all the data points.

2. Divide the sum by ‘N’. The result will be your mean.

Example: If you have five test scores (80, 85, 90, 95, and 100), then add them up (80+85+90+95+100 = 450) and divide by ‘N’ (5) to get the mean (450/5 = 90).

**Step 4: Calculate deviations**

For each data point in your dataset:

1. Subtract the mean from that point.

2. Square the result obtained.

This will give you squared deviations for each data point. It’s important to note that squaring deviations ensures that any negative difference won’t affect the overall calculation.

**Step 5: Sum up squared deviations**

Add up all squared deviations to get their combined total.

**Step 6: Divide by ‘N – 1’**

Divide the sum of squared deviations by ‘N – 1’. By using ‘N – 1’ instead of ‘N’, we incorporate the concept of degrees of freedom which helps account for variations in data sample sizes and ensures better accuracy in the calculations.

**Step 7: Calculate the square root**

The last step is to take the square root of the result obtained in the previous step. This will give you the standard deviation for your dataset.

Example: Let’s consider our five test scores again (80, 85, 90, 95, and 100). The mean was found to be 90. The squared deviations are (10^2, 5^2, 0^2, 5^2, and 10^2) or (100, 25, 0, 25, and 100). Summing these values gives us 250. Now divide this by ‘N-1’ (4) to get 62.5. Finally, take the square root of this number, which gives a standard deviation of approximately 7.91.

By following these steps on a calculator that has basic arithmetic functions like addition, subtraction, multiplication/division, and square root extraction capabilities, you can quickly calculate the standard deviation for any dataset. Some advanced calculators also have built-in functions for calculating standard deviations directly by inputting your data points; refer to your specific calculator’s manual for instructions on how to use such features.