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Jan
22
comment Sum of Squares reference resources
Good books on regression that I have read are listed below. A good introduction: Miles, J., & Shevlin, M. (2001). Applying Regression and Correlation: A guide for students and researchers. LA: Sage. More advanced (lucidly written nevetheless): Cohen, J., Cohen, P., West, S. G., & Aiken, L. S. (2003). Applied multiple regression/correlation analysis for the behavioral sciences (3rd ed.). Mahwah, NJ: Lawrence and Erlbaum.
Jan
22
comment Sum of Squares reference resources
Few textbooks that I've come across introduce regression by using the term sum of squares. It's more common to introduce the term when referring to analysis of variance (ANOVA). If you're taking a course in statistics I would recommend working on the practicals rather than theory. There will always be more time for theory later :) Try browsing a few introductory text books in statistics at your library. I could provide you with several recommendations on general books, but none of them introduces sum of squares in the context of regression.
Jan
22
comment Differences between groups
I hope this helps: statisticshell.com/docs/contrasts.pdf
Jan
22
revised Sum of Squares reference resources
New section on SST and SSR
Jan
22
comment Sum of Squares reference resources
In a graph with data points along the axes x and y, the total sum of squares SST represents how much the position of each observed data point deviates from the mean. In the same plot, we could draw a line that fits between all the data points. This line approximates the original observations. If we only had access to the line, but not the original observations, we would find that all the estimations of the original data points are - by definition - present on this line. The deviation of our newly estimated points from the mean of the observed values would give us an error term: the SSR.
Jan
21
comment Differences between groups
You need to calculate one sum for each treatment. You then apply the contrast on these sums.
Jan
21
comment Differences between groups
Will you do calculations by hand or are you using any particular software (SPSS, Excel, R)? It would make things easier to explain.
Jan
21
revised Sum of Squares reference resources
Added Sxx, Syy, Sxy
Jan
21
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Jan
21
comment Sum of Squares reference resources
Sxx is the distance from the sample (x) to the mean (x bar). Because Sxx is written with Sigma we say "For every x, sum the results of...". Thus, Sxx takes one sample at a time, subtracts the mean, and squares the result. Data set x = 3, 4.5, 6 The mean of x (x bar) = 4.5 y = 1, 4, 12 The mean of y (y bar) = 5.67 Sxx = SQR(3 - 4.5) + SQR(4.5 - 4.5) + SQR(6 - 4.5) Syy = SQR(1 - 5.67) + SQR(4 - 5.67) + SQR(12 - 5.67) Sxy = (3 - 4.5)*(1 - 5.67) + (4.5 - 4.5)*(4 - 5.67) +(6 - 4.5)*(12 - 5.67) I've edited the answer. See above. It's should be easier to read.
Jan
21
revised Sum of Squares reference resources
Flipped two sentences.
Jan
21
answered Sum of Squares reference resources
Jan
21
answered Differences between groups
May
2
comment Weibull distributed data for correlation analysis
Great! Looks more normal. Thanks.
May
2
comment Weibull distributed data for correlation analysis
OK, so using the Box-Cox SPSS syntax provided in the link above, I was able to estimate the lambda with the least skew at 0.1. Have I then understood correctly that I would need to apply the transform, like so (X^0.1 - 1) / 0.1
May
2
asked Weibull distributed data for correlation analysis
May
2
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30
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30
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