Those examples were pretty straightforward. The data points fell very neatly along the line. Real data are rarely like this. As you remember from the lesson on level change, data are often variable, which can make it challenging to estimate the slope. Let’s look at an example. Even though the data points don’t fall exactly along this blue line, it is a pretty good estimate of the direction of the data. These data are moving in an upward direction as time goes on, so this graph has an increasing slope.