We expect our exam scores will be pretty close to the normal distribution, but let’s confirm that graphically (it’s difficult to see from the data alone!). Values outside two standard deviations are considered outliers. We expect 68% of values to fall within one standard deviation of the mean, and 95% to fall within two standard deviations.

It means we know the probability of how many values occurred close to the mean. The normal distribution curve is a graphical representation of the normal distribution theorem stating that “…the averages of random variables independently drawn from independent distributions converge in distribution to the normal, that is, become normally distributed when the number of random variables is sufficiently large”.īit of a mouthful, but in essence, the data converges around the mean (average) with no skew to the left or right. What’s the average score? Did more students score high or low? How clustered around the average are the student scores? Are the scores normally distributed or skewed? What is a Normal Distribution Curve? In this example, I have 1,000 exam scores between 0 and 100, and I want to see what the distribution of those scores are. What is a Histogram?Ī histogram is a graphical representation of the distribution of a dataset.

It’s a really useful visual technique for determining if your data is normally distributed, skewed or just all over the place. In this tutorial you’ll learn how to make a histogram in Google Sheets with a normal distribution curve overlaid, as shown in the above image, using Google Sheets. Histogram and Normal Distribution chart made in Google Sheets

How to make a histogram in excel mac