How to use the practice test score trend analyzer
Look at one practice test and you are improving; look at the next and you are not. Enter your scores oldest first, one per line, and a least-squares linear regression gives the direction of the whole run and the size of the change per sitting, alongside the step-to-step change and a 3-test moving average. Labels are optional, so a bare list of scores works too.
The direction comes from the regression slope. When the slope sits within 0.01 points per test of zero the run is reported as flat rather than being pushed into a direction it does not have. The R-squared value says how closely the scores hug that line, and when every score is identical there is no spread to explain, so that row is hidden instead of showing a meaningless number.
One point matters more than the rest: the extended trend value is not a forecast. It is simply where the fitted line would sit one step further along. Practice tests differ in content, difficulty and how rested you were, so there is no reason the next score should land on a straight line. Read it as the shape of the run so far, not as the score you are going to get.
At least 3 scores are needed. With 2, a line passes exactly through both points and the trend says nothing, and a 3-test moving average cannot be formed. Percentiles and score band conversions are not handled here.
Frequently asked questions
No. It is where the straight line fitted to your past scores would sit one step further along, and nothing more. Test difficulty and content change from sitting to sitting, so a real score can land well off that line.
A simple least-squares linear regression with the sittings numbered 1, 2, 3 and so on, which gives the slope and the R-squared value. The moving average in the table is a separate figure, the plain mean of the last 3 scores.
At least 3. With only 2 scores a straight line passes exactly through both points, so the trend carries no information, and a 3-test moving average cannot be formed.