15. Video: Measures of Center (Median)

The Median

The median splits our data so that 50% of our values are lower and 50% are higher. We found in this video that how we calculate the median depends on if we have an even number of observations or an odd number of observations.

Median for Odd Values

If we have an odd number of observations, the median is simply the number in the direct middle . For example, if we have 7 observations, the median is the fourth value when our numbers are ordered from smallest to largest. If we have 9 observations, the median is the fifth value.

Median for Even Values

If we have an even number of observations, the median is the average of the two values in the middle . For example, if we have 8 observations, we average the fourth and fifth values together when our numbers are ordered from smallest to largest.

In order to compute the median we MUST sort our values first.

Whether we use the mean or median to describe a dataset is largely dependent on the shape of our dataset and if there are any outliers . We will talk about this in just a bit!