How to compare the slopes of two regression lines?
SlopesTest(Rx1, Ry1, Rx2, Ry2, b, lab): outputs the standard error of the difference in slopes sb1–b2, t, df and p-value for the test described above for comparing the slopes of the regression lines for the two samples.
How to compare the slopes for two independent statistics?
Note that while the null hypothesis that β = 0 is equivalent to ρ = 0, the null hypothesis that β1 = β2 is not equivalent to ρ1 = ρ2. Example 1: We have two samples, each comparing life expectancy vs. smoking. The first sample is for males and the second for females.
What’s the difference between slope for men and women?
As can be seen from the scatter diagrams in Figure 1, it appears that the slope for women is less steep than for that for men. In fact, as can be seen from Figure 2, the slope of the regression line for men is -0.6282 and the slope for women is -0.4679, but is this difference significant?
How to find the difference between slopes and intercepts?
If there is no significant difference in the slopes, determine whether there is a significant difference in the intercepts. Using the formula =SlopesTest (A5:A12,B5:B12,D5:D13,E5:E13,,TRUE) in range A15:B18, we see that there is no significant difference between the two slopes (p-value = .75 > .05 = alpha).
How to get confidence interval for slopes of linear regression?
Using Prism’s nonlinear regression analysis to also compute the confidence interval for the difference between slopes? Prism’s linear regression analysis can compare slopes and report a P value. But it doesn’t report a confidence interval for the difference or ratio of the slopes. However Prism’s nonlinear regression analysis can do this.
When to use slopes to compare growth patterns?
Comparing scaling parameters (i.e. slopes) between groups can be used by biologist to assess different growth patterns or the development of different forms or shapes between groups. For examples, the regression between head size and body size may be different between males and females if they grow differently.