What Is a Trend Line?
A trend line is a straight line intersecting a group of data points on a graph; its location and slope are determined through statistical analysis. Once a student has taken the requisite number of Star tests (with at least one of them being an Enterprise test), a trend line can be calculated using the Scaled Scores as data points. The Scaled Score that falls on the trend line at a particular time is the trend score.
A trend line cannot be calculated for a student who has taken less than the minimum required number of tests (see list of reports below).
Imagine that a student has taken five Star Reading Enterprise tests since the beginning of the school year. That student's Scaled Scores (blue dots) are shown below, along with the calculated trend line (red).
Less than a month later, the student takes another Star Reading Enterprise test, and gets a Scaled Score of 550, which is a significant jump for such a short period of time; the score from the test prior to this was only a little over 400. It is possible that the student just made several lucky guesses during the most recent test, explaining the unusually large rise in the Scaled Score. The trend line suggests that on the date of the latest test, the student should probably have scored closer to 496.
It is important to collect information and look for patterns, or trends, in the information instead of placing too much emphasis on a single score. Looking at the trend line and a student's performance over time will provide a more accurate picture of that student's performance and growth. A trend line marginalizes score fluctuations and allows you to see patterns of achievement; more data points help ensure a highly accurate trend line.
Reports that show trend lines include: