![]() Use prediction bands when your main goal is show the variation in your data. Prediction bands are wider, to also include the scatter of the data. Use confidence bands to learn how precisely your data define the best-fit line. The confidence bands sort of combine the confidence intervals of the slope and intercept in a visual way. When to plot confidence and prediction bands This graph shows both prediction and confidence intervals (the curves defining the prediction intervals are further from the regression line). In contrast, the 95% confidence band is the area that has a 95% chance of containing the true regression line. The 95% prediction band is the area in which you expect 95% of all data points to fall. The prediction bands are further from the best-fit line than the confidence bands, a lot further if you have many data points. Prism can also plot the 95% prediction bands. This is not the same as saying it will contain 95% of the data points. The confidence bands are 95% sure to contain the best-fit regression line. Many data points will be outside the 95% confidence bands. Given the assumptions of linear regression, you can be 95% confident that the two curved confidence bands enclose the true best-fit linear regression line, leaving a 5% chance that the true line is outside those boundaries. The figure below shows four possible linear regression lines (solid) that lie within the confidence band (dashed). Rather, the curved lines are the boundaries of all possible straight lines. This does not mean that the confidence band includes the possibility of curves as well as straight lines. Two confidence bands surrounding the best-fit line define the confidence interval of the best-fit line. Or double click on the graph, and use the middle tab of Format Graph to add the other regression data set. So go to the graph with the first regression line, and drag the second regression analysis onto that graph. The regression lines (and bands) are data sets that you can add to any graph by drag-n-drop or using the Change menu from the graph. To plot both on one graph, you need to analyze your data twice, choosing a confidence band the first time and a prediction band the second time. ax sns.regplot (x, y, ci80) The regplot () function works in the same manner as the lineplot () with a 95 confidence interval by default. Prism lets you choose either a confidence band or a prediction band as part of the linear regression dialog. ![]() Plotting both confidence and prediction bands on the same graph You can also choose to fill the area enclosed by the confidence or prediction bands. To adjust the appearance of the confidence or prediction bands, go to the Format Graph dialog, select the dataset that represents the regression line, and adjust the error bars and area fill settings. If you check the option box on the top of the Simple linear regression parameters dialog, Prism will calculate and graph either the 95% confidence band or 95% prediction band of the regression line.
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