How to Play Best Fit Blitz

Your goal is to place a straight line that best represents the overall pattern in each scatterplot. You do not need to calculate a slope or intercept. The challenge is to make one visual estimate before the ordinary least-squares answer appears.

Pointer and touch controls

1. Look at the whole cloud of electric-blue points and decide whether the trend rises or falls.
2. Drag either coral endpoint. The left handle controls the left half of the line and the right handle controls the right half.
3. Adjust both height and slope until the gaps above and below feel balanced across the graph.
4. Select Submit Line. The line locks, the dashed mint benchmark appears, and pale vertical residuals show the benchmark errors.
5. Read the round score, then move to the next scatterplot. Five rounds make one complete game.

Keyboard controls

Focus the plot with Tab. The selected endpoint has a larger coral ring. Press Space or Enter to switch between the left and right handles. Use the arrow keys to move the selected handle by one tenth of a graph unit. Hold Shift with an arrow key to move by one quarter of a unit. The plot announces the selected handle and its updated coordinates to assistive technology.

Reading the reveal

The solid coral line is your submitted estimate. The dashed mint line is the ordinary least-squares benchmark. Each pale vertical segment connects a point to the benchmark prediction at the same x-value; that segment is a residual. The displayed excess SSE is the amount by which your squared residual total exceeds the minimum. The normalized value divides that excess by SST, the total y variation for the round. Lower normalized excess means a higher score.

Starting another run

Select New Seed at any time to reset the game with another repeatable five-round set. After round five, Play Again restarts the same seed so you can compare a second attempt. A seed in the page URL reproduces the same synthetic data, which is useful for a shared classroom discussion or a bug report.