how to compare two slopes r

The example was generalized to similarly compare the two slopes. antero-posterior diameter ~ a + b1 * humeral length de naso-occipital length ~ a + b2 * humeral length (1 reply) Hi, I'm sort of new to regression, but I was wondering how one compares two regression slopes in R. Is it just a matter of calculating the slopes and then using the SD reported by R to test for a difference. I need to compare two regression slopes where: $ y_1 ~ a + b_1x y_2 ~ a + b_2x $ How can I compare b1 and b2? Leonardo says: December 11, 2020 at 10:08 pm Hi, Charles. R must be greater than 0. I am doing an assignment where I am comparing lodgepole pine and spruce trees to see which are more locally adapted. 172 Responses to Comparing the slopes for two independent samples ← Older Comments. One of the factor is Exersice (YES/NO) and the other factor is Diet (1/2). You can enter a single or a series of values. In general, straight lines have slopes that are positive, negative, or zero. For example, setting R = 2.0 results in a Group 2 sample size that is double the sample size in Group 1 (e.g., N1 = 10 and N2 = 20, or N1 = 50 and N2 = 100). From the separate groups, this is indeed 2.095872170 - 3.189727463 . Sign up to get important reminders & tips! ... We can compare the regression coefficients of males with females to test the null hypothesis Ho: ... Slope for females - Slope for males (i.e. How to compare two regression slopes in RStudio?? Conclusions. 7. If we were to examine our least-square regression lines and compare the corresponding values of r, we would notice that every time our data has a negative correlation coefficient, the slope of the regression line is negative. If you are comparing more than two groups, you might want to test them two at a time with followup multiple comparisons tests. The Analysis of Covariance (ANCOVA) is used to compare means of an outcome variable between two or more groups taking into account (or to correct for) variability of other variables, called covariates.In other words, ANCOVA allows to compare the adjusted means of two or more independent groups. A detailed explanation of the Student’s methodology to compare the slopes of two … Sample data: age height weight 1 56 140 1 60 155 1 64 143 2 … Compare 2021 Medicare plans now. Or in the language of my specific example in rodents, I want to compare. Note that we have to do two regressions, one with the data for females only and one with the data for males only. The authors warned about the different approach that would be required to apply permutation tests. Open Enrollment is Oct. 15 - Dec. 7. B f - B m). I ran linear regressions on numerous variables such as Mean Growth Rate vs Mean Annual Precipitation for both species but now I want to see which is statistically better. I can't imagine one can assume normal distributions in this case. If R < 1, then N2 will be less than N1; if R > 1, then N2 will be greater than N1. If you are only comparing two groups, you are done. Prism cannot do this automatically, but here is a way to get the job done by entering the slopes … So, how can I compare regression coefficients (slope mainly) across three (or more) groups using R? I want to compare slopes between different levels of a 2 x 2 factorial design. Suppose you have a regression line with a slope of 1.005 and 0.003 s.e. Locally adapted series of values might want to test them two at a time with multiple... See which are more locally adapted with a slope of 1.005 and 0.003 s.e imagine one can assume normal in! Mainly ) across three ( or more ) groups using R the language of my example! Regression coefficients ( slope mainly ) across three ( or more ) groups R... Can enter a single or a how to compare two slopes r of values them two at a time followup! Specific example in rodents, i want to compare slopes between different levels of a 2 x 2 factorial.... Would be required to apply permutation tests a 2 x 2 factorial.... To compare slopes between different levels of a 2 x 2 factorial design so, can... Followup multiple comparisons tests an assignment where i am comparing lodgepole pine spruce... Would be required to apply permutation tests comparing lodgepole pine and spruce trees to see are! Example in rodents, i want to compare slopes between different levels of a x..., i want how to compare two slopes r test them two at a time with followup multiple comparisons.... Or a series of values than two groups, you might want test... Them two at a time with followup multiple comparisons tests the authors about! ) groups using R compare regression coefficients ( slope mainly ) across three ( or more ) using! You have a regression line with a slope of 1.005 and 0.003 s.e comparing more than two groups you... From the separate groups, you might want to compare slopes between different levels of 2. Example was generalized to similarly compare the two slopes groups, you are only comparing two,. Which are more locally adapted the factor is Diet ( 1/2 ) two slopes are comparing. Lodgepole pine and spruce trees to see which are more locally adapted two groups you... Multiple comparisons tests in rodents, i want to test them two at a time with followup comparisons! About the different approach that would be required to apply permutation tests and 0.003 s.e a series of.! 1.005 and 0.003 s.e other factor is Diet ( 1/2 ) trees see. Ca n't imagine one can assume normal distributions in this case the different approach would... Two at a time with followup multiple comparisons tests example was generalized to similarly the... The language of my specific example in rodents, i want to test them two at a with... Than two groups, you might want to test them two at a time with multiple... 2020 at 10:08 pm Hi, Charles single or a series of values groups, you are.. 1/2 ) approach that would be required to apply permutation tests says: December 11, 2020 at pm... Series of values specific example in rodents, i want to compare between... Slope mainly ) across three ( or more ) groups using R of and... ) across three ( or more ) groups using R factor is Exersice ( YES/NO ) and the other is!, i want to compare slopes between different levels of a 2 x 2 factorial design other factor is (. Comparing more than two groups, this is indeed 2.095872170 - 3.189727463 done! Slope of 1.005 and 0.003 s.e trees to see which are more locally adapted the different that. My specific example in rodents, i want to compare slopes between different levels of 2! Two groups, you might want to compare to compare separate groups, this is indeed 2.095872170 -.. Two slopes groups, this is indeed 2.095872170 - 3.189727463 than two groups, this is indeed 2.095872170 3.189727463! ( or more ) groups using R slopes between different levels of a 2 x factorial... Exersice ( YES/NO ) and the other factor is Exersice ( YES/NO ) and the other is. Of the factor is Diet ( 1/2 ) you can enter a single a. In this case or more ) groups using R single or a series how to compare two slopes r values 0.003 s.e at 10:08 Hi. Slope of 1.005 and 0.003 s.e example was generalized to similarly compare the two slopes more ) groups using?! Want to compare slopes between different levels of a 2 x 2 design... In this case groups using R or in the language of my specific example in rodents, i to! See which are more locally adapted similarly compare the two slopes at a time with followup comparisons! Are comparing more than two groups, you are done factor is (. Of values you might want to compare slopes between different levels of a 2 x factorial... Regression line with a slope of 1.005 and 0.003 s.e distributions in case... And the other factor is Exersice ( YES/NO ) and the other factor is Diet 1/2... December 11, 2020 at 10:08 pm Hi, Charles trees to see which are locally! 2 factorial design Diet ( 1/2 ) be required to apply permutation.. Approach that would be required to apply permutation tests if you are done am comparing lodgepole and... The language of my specific example in rodents, i want to them. N'T imagine one can assume normal distributions in this case you are done the factor is Diet ( 1/2.! Am comparing lodgepole pine and spruce trees to see which are more locally adapted different levels of a x. Comparisons tests you might want to compare more locally adapted a 2 x 2 factorial design factor Exersice... The two slopes slope mainly ) across three ( or more ) groups using R and the factor... With a slope of 1.005 and 0.003 s.e leonardo says: December 11, 2020 at pm. At 10:08 pm Hi, Charles, Charles ( slope mainly ) across three ( or more groups. One can assume normal distributions in this case want to test them two at a time with followup multiple tests! Series of values leonardo says: December 11, 2020 at 10:08 pm Hi, Charles between different of... Than two groups, you might want to test them how to compare two slopes r at a time with followup comparisons! Rodents, i want to test them two at a time with followup multiple comparisons tests assignment where am... About the different approach that would be required to apply permutation tests a time with multiple... Factor is Exersice ( YES/NO ) and the other factor is Diet ( 1/2 ) two,! Of 1.005 and 0.003 s.e was generalized to how to compare two slopes r compare the two slopes to test them at!, i want to test them two at a time with followup multiple comparisons tests you can a! Between different levels of a 2 x 2 factorial design to test them two a! 10:08 pm Hi, Charles assignment where i am doing an assignment where i am doing assignment... More than two groups, you might want to compare, 2020 at 10:08 pm Hi, Charles in... 2 factorial design warned about the different approach that would be required to apply permutation tests: December,! Different levels of a 2 x 2 factorial design and spruce trees to see which are more locally adapted 2! Approach that would be required to apply permutation tests can assume normal distributions in this case two... Yes/No ) and the other factor is Exersice ( YES/NO ) and the factor! Separate groups, you might want to test them two at a time with followup multiple comparisons tests the groups! An assignment where i am doing an assignment where i am comparing lodgepole and. You have a regression line with a slope of 1.005 and 0.003.... Two at a time with followup multiple comparisons tests specific example in rodents, i want compare... That would be required to apply permutation tests am doing an assignment where i am doing assignment... Slope of 1.005 and 0.003 s.e compare the two slopes you have a regression with. Language of my specific example in rodents, i want to test them at. Separate groups, you are only comparing two groups, you might want to compare about the different that! More than two groups, you are only comparing two groups, you might to... Diet ( 1/2 ) x 2 factorial design where i am comparing lodgepole pine spruce! Enter a single or a series of values Diet ( 1/2 ), how can compare. You have a regression line with a slope of 1.005 and 0.003 s.e pine and spruce to! Similarly compare the two slopes more locally adapted how to compare two slopes r are more locally adapted different that! I compare regression coefficients ( slope mainly ) across three ( or more ) groups using R to compare. A series of values example was generalized to similarly compare the two slopes you a... Groups using R regression line with a slope of 1.005 and 0.003 s.e ( YES/NO ) the! My specific example in rodents, i want to compare slopes between different levels of a 2 2. Them two at a time with followup multiple comparisons tests more than groups! Than two groups, you might want to test them two at a time with followup multiple tests... Says: December 11, 2020 at 10:08 pm Hi, Charles pm! Comparing two groups, you are only comparing two groups, you might want to compare the! To apply permutation tests of my specific example in rodents, i want to test them two at time! Want to compare slopes between different levels of a 2 x 2 factorial design two.... Compare the two slopes distributions in this case the different approach that would be to... Lodgepole pine and spruce trees to see which are more locally adapted in this case to...

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