X-bar -- written as the letter "x" with a straight line or bar above it -- is statistical shorthand for the average, or arithmetic mean -- or average -- of x. Calculating it is the same as calculating the mean of x, where x can be any continuous variable, such as age, height or weight. The x-bar is used to represent the sample mean; that is, the mean of a sample rather than an entire population. The mean of the entire population is usually represented by the Greek letter mu.

### Step 1

Add up all the values of x. For example, if you have a sample of weights of adults and you get 150, 160, 170, 180 and 190, add these to get 850.

### Step 2

Count the number of values of x. In the example, there are five weights.

### Step 3

Divide the sum by the number of values. In the example, 850/5 = 170.