A prediction interval is a confidence interval about a Y value that is estimated from a regression equation. Copy the above formulas down, plot the results on a chart, and you will have a clear visual representation of the predicted values and the confidence interval: The FORECAST.ETS.SEASONALITY function is used to calculate the length of a recurring pattern in the specified timeline. The syntax of FORECAST.ETS.SEASONALITY is as follows: For our data set, the formula takes the following shape: =FORECAST.ETS.SEASONALITY(B2:B22, A2:A22). It is calculated using the following general formula: Confidence Interval = (point estimate) +/- (critical value)* (standard error) A smaller interval would imply more confidence in the prediction for this specific point. The function has the following arguments: As you see, the syntax of FORECAST.ETS.CONFINT is very similar to that of the FORECAST.ETS function, except this additional argument: Confidence_level (optional) - a number between 0 and 1 that specifies a level of confidence for the calculated interval. The FORECAST.ETS.CONFINT is available in Excel for Office 365, Excel 2019, and Excel 2016. My formula is "=FORECAST.LINEAR(I2,$C2:$H2,$C1:$H1)" 531.48 ± 1.96 (6.21) = [ 519.3, 543.6]. You will like it! The Excel FORECAST.ETS.CONFINT function is new in Excel 2016. Formula to calculate prediction interval is . The confidence interval helps you figure out the accuracy of the prediction. Prediction Interval. What am I missing here? The formula I found online for all but the correct draw is: =IF (A3&B3=C3&D3),3,IF (AND (A3=B3,C3=D3),1,IF (AND (A3>B3,C3>D3),1,IF (AND (A3