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kurofufu · ‎01-31-2013

The monthly sales amount of a retail store(S) is positively correlated with the number of visiting customers(C). The regression model of S on C has a positive regression coefficient for C. But after I add some additional variables, the reg coefficient for C continues to be significant but becomes negative. Should I include C in the model? If so, the interpretation of C effect will not make sense at all. Any ideas?

kurofufu · ‎01-04-2013

A/B testing and Multivariate Testing(MVT) are popular testing methods used in web analytics. Can anyone tell me which statistical procedures I should use for these testings?

kurofufu · ‎01-02-2013

I run model comparison node and open the results window, but only see Score Distribution, Score Rankings, Fit Statistics and Output windows. I would like to know how to open ROC curve winodw.

kurofufu · ‎11-12-2012

I just checked. Three regression have the same number of Ns and no missing values in X1 and X2.

kurofufu · ‎11-09-2012

The fitted model using X1 and X2 is Y = 0.5 + 1.2*X1 + 1.1*X2 + e This equation tells me that if I increase one unit in X2 while X1 remains constant, Y will increase 1.1. Is this a wrong conclusion given that when Y is regressed on X1 only, X1 is not significant?

kurofufu · ‎11-09-2012

Will R replace SAS/STAT someday? Now big internet companies such as Google, Facebook etc only look for people with R skills.

kurofufu · ‎11-09-2012

The adjusted R-square is the same - R-square = 0.7598, Adj R-square = 0.7581 The interaction term X1*X2 is NOT significant.

kurofufu · ‎11-09-2012

If Y is regressed on X1 only, R-square is 0.72 and the X1's coefficient is significant. If Y is regressed on X2 only, R-square is 0.002 and the X2's cofficient is NOT significant. If Y is regressed on X1 and X2, R-square is 0.76 and the coefficients of both X1 and X2 are significant. Questions: 1. Why X2 becomes significant when it is combined with X1? Is there a more intuitive explanation for this? 2. Should I use X2 in the final model?

kurofufu · ‎10-26-2012

thanks for the great answer, pagemiller.

kurofufu · ‎10-26-2012

Ok, let's focus on predictive modeling for this question. When we create a regression model for prediction, don't all coefficients included in the model need to be significant?

kurofufu · ‎10-26-2012

GLM also produces the same result as REG.

kurofufu · ‎10-26-2012

Sir, we are creating a regression equation for prediction, not for comparison of two groups.

kurofufu · ‎10-26-2012

Don't you need to report significance information when presenting a regression equation?

kurofufu · ‎10-26-2012

I understand c0 not equal to b0 and two equations are equivalent agebraically. But since c0 is not significant, how can we adopt the second equation?

kurofufu · ‎10-26-2012

Use regression equations to explain my question First case: Y= b0 + b1 * X1 + .... 2nd case: Y = c0 + c1 * X1 + ... b0, b1 are significant c0 is not significant, c1 is signficant So which one I should use? Which one is correct?

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a regression model question

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a regression model question

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R replaces SAS/STAT?

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Re: Indicator Variable in PROC REG

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Re: Indicator Variable in PROC REG

Re: Indicator Variable in PROC REG

Re: Indicator Variable in PROC REG

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