<p><a href="https://www.prepswift.com/quizzes/quiz/prepswift-calculating-sd-simple-cases" target="_blank">Calculating SD (simple cases) Exercise</a></p><p>Standard deviation can get quite complex. The good news is we can understand A LOT of its behavior by <strong><span style="color:#8e44ad;">Calculating Standard Deviation in Simple Cases</span></strong>.</p>
<p><strong><span style="color:#27ae60;">1. The Simplest Case: Only one number in the dataset (or every number is the same).</span></strong></p>
<p>If there's only one number in the dataset, then it is not "spread out" at all. The standard deviation is $0$. If there are $10$ numbers, but they all equal $5$, then the data is not "spread out" at all. The standard deviation is $0$.</p>
<p><strong><span style="color:#27ae60;">2. The Second Simplest Case: Exactly two numbers inn the dataset.</span></strong></p>
<p>With two numbers in the dataset, find the standard deviation by following these steps:</p>
<p style="margin-left: 40px;"><strong><u>Step 1</u></strong>: Calculate the average of the two numbers.</p>
<p style="margin-left: 40px;"><strong><u>Step 2</u></strong>: Subtract the lower number from the average found in step 1. </p>
<p>That's it, lol. You're done. You could also just find the "positive difference" between the average and the larger number. You get the same answer.</p>
<p style="margin-left: 40px;"><strong><span style="color:#e74c3c;">Example</span></strong></p>
<p style="margin-left: 40px;"><em>What's the standard deviation of a dataset that includes only the numbers $10$ and $22$?</em></p>
<p style="margin-left: 40px;">The average of the two numbers is $16$, so the standard deviation is...</p>
<p>$$\sigma = 16 - 10 = 6$$</p>