Regression Prediction Interval
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Tap a term to see what it means, or .
Calculate
Example: ad spending (x, in thousands) and sales (y, in thousands of units) over eight months. If next month's spending is 6.5, in what range should sales fall? Change the values to work out your own case.
Step by step
What each term means
- Point Prediction (ŷ₀)
- The line's value at x₀: the best guess for y.
- Critical Value t
- From the t distribution with n − 2 degrees of freedom, for the chosen confidence.
- Residual Standard Error (s)
- How much the points spread around the line, on average.
- Root of the Uncertainty
- The 1 is a new value's variation around the line, which doesn't shrink with more data; 1/n and the (x₀ − x̄)² term are the uncertainty of the line itself. Without the 1, you get the confidence interval for the mean.