What is the coefficient of correlation between sales and price?

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Discussion Overview

The discussion revolves around the calculation of the coefficient of correlation between sales and price based on a provided dataset. Participants explore the relationships between various statistical concepts such as the coefficient of determination, variance, and sum of squares, while seeking clarification on how these concepts interrelate in the context of the problem.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Homework-related, Mathematical reasoning

Main Points Raised

  • One participant notes an inverse relationship between sales and price, mentioning a coefficient of determination of 106% and a variance of sales around the mean of 640, questioning how to derive the coefficient of correlation from this information.
  • Another participant expresses uncertainty about the meaning of "variance of sales around mean," seeking clarification.
  • Several participants inquire whether the sum of squares total is equivalent to the variance around the mean, indicating confusion about these statistical terms.
  • One participant suggests that variance is related to the coefficient of determination, which is the square of the coefficient of correlation, but acknowledges potential misunderstanding regarding the adjusted coefficient of determination.
  • A different participant introduces an alternative definition of the coefficient of correlation, relating it to covariance and standard deviations, proposing that this might be relevant to the problem at hand.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the statistical concepts involved, with no consensus reached on the definitions or relationships between the terms discussed. Multiple competing views and uncertainties remain evident throughout the discussion.

Contextual Notes

Participants have not resolved the definitions of variance, sum of squares, and their relationships to the coefficient of determination and correlation. There are also unresolved mathematical steps related to the calculations needed to find the coefficient of correlation.

adeel
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In a sample of 21 observations obtained it was found that sales and price have an inverse relationship and coefficient of determination is 106% as much as the adjusted coefficient of determination. It is also known that the variance of sales around mean is 640. What is the coefficient of correlation?

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Im not sure how all the information fits together. I know coefficient of determination is SSR/SST, but i don't have any of that information
 
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im not really sure what variance of sales around mean, means...help?
 
is sum of squares total the same as the variance around the mean?
 
adeel said:
is sum of squares total the same as the variance around the mean?

Variance is the coefficient of determination, which is the square of the coefficient of correlation. Adjusted, I think, means calculated from a linear regression with outliers eliminated. However, I may be totally wrong :redface:. In any case, http://encyclopedia.thefreedictionary.com/Coefficient+of+determination might help.
 
Another way coef of corr between X and Y is defined is Corr(X,Y) = Cov(X,Y)/([itex]\sigma_X\sigma_Y[/itex]) where "sigma" is the standard dev. of the subscripted variable. Maybe it is this formula that the problem is asking about?
 

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