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Data Analysis Basics

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Summarizing Data: Mean, Median, Mode

2:35 with Ben Deitch

There's more than one way to talk about the 'middle' of a dataset. In this video we'll look at mean, median, and mode and see when you might want to use each one!

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    Now that we've got some bounds for 0:00
    our data, it would be nice to know where the middle is. 0:01
    Unfortunately, there is a few different ways to define the middle. 0:05
    Let's look at three of them. 0:08
    The first and most common way to look at the middle of a data set 0:10
    is to use the mean, also known as the average. 0:13
    To find the average of a set, add up all the values and 0:16
    then divide by how many values there are. 0:20
    One problem with averages is that they're easily influenced by outliers. 0:22
    If we're looking at these eight bowling scores, 0:27
    the average is higher than every value but the highest. 0:29
    In this case, instead of using the average to find the middle, 0:33
    it might be better to use the median. 0:36
    The median represents the middle value in a data set. 0:39
    If your data set has an even number of values and thus no true middle value, 0:42
    then the median is the average of the two middle values. 0:48
    So for our bowling data set, the median value would be 115, which 0:51
    does a much better job of representing the middle than the average did. 0:56
    The last way we can try and find the middle is to use the mode. 1:00
    The mode is them most frequent value in our data set. 1:04
    In our bowling data set, there's only one repeated value, so our mode has to be 90. 1:07
    Back in the spreadsheet, let's calculate these values for our data set. 1:12
    Let's add the labels starting at A5, average, 1:17
    median and mode. 1:21
    And then let's highlight those labels and hit command or ctrl B to make them bold. 1:26
    Then in column B let's use functions to figure out these values. 1:31
    In B5, let's type =AVERAGE. 1:35
    Hit Enter to select it, paste in our range, hit Enter again and there we go. 1:40
    Now let's do the same thing for the median and mode. 1:47
    Type in the function, 1:51
    paste in the range, and hit Enter. 1:56
    And there we go, except for the mode, 2:03
    looks like it's not using the right data type. 2:06
    So let's click this button up here, and 2:10
    instead of Automatic let's set it to Duration. 2:12
    There we go. 2:18
    All right, not only do we have information about the edges of our data but 2:19
    now we have a pretty good idea of where the middle is. 2:24
    If you'd like to learn more about mean, median and 2:27
    mode, check out the teacher's notes. 2:29
    Coming up, we'll look at a few ways to figure out the spread of our data. 2:31

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