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#1
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regression analysis
Hi,
I'm trying to figure out OLS regression with excel. Can anyone tell me why the data analysis toolpak gives me ANOVA results? Also, does anyone know an easy method for creating dummy varibles? Thanks |
#2
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regression analysis
Hi,
I'm afraid I don't know what OLS is, but in the spreadsheet you can look at the LINEST function or LOGEST. There is a fairly good help on these functions. You can also get a couple of linear regression lines and formulas using the chart tool. By dummy variables do you mean some random data? If so then you have =RAND() and RANDBETWEEN(1,100) in the spreadsheet and a random number generator in the Analysis ToolPak. -- Thanks, Shane Devenshire "usedtostata" wrote: Hi, I'm trying to figure out OLS regression with excel. Can anyone tell me why the data analysis toolpak gives me ANOVA results? Also, does anyone know an easy method for creating dummy varibles? Thanks |
#3
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regression analysis
The ANOVA table evaluates the significance of the model as a whole, vs. the
t-tests below it in the output that evalute the significance of individual fitted coefficients. Can you be more specific about your dummy variable question? Jerry "usedtostata" wrote: Hi, I'm trying to figure out OLS regression with excel. Can anyone tell me why the data analysis toolpak gives me ANOVA results? Also, does anyone know an easy method for creating dummy varibles? Thanks |
#4
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regression analysis
Cheers Shane!
OLS stands for ordinary least squares- it's the same thing as linear regression (LINEST). I've been through the help thing already and it's pretty useful, but it doesn't tell you how to deal with categorical variables in regressions. Dummy variables are the solution to using categorical variables in regressions- it's when you substitute binary variables for the composites of categorical variables. "ShaneDevenshire" wrote: Hi, I'm afraid I don't know what OLS is, but in the spreadsheet you can look at the LINEST function or LOGEST. There is a fairly good help on these functions. You can also get a couple of linear regression lines and formulas using the chart tool. By dummy variables do you mean some random data? If so then you have =RAND() and RANDBETWEEN(1,100) in the spreadsheet and a random number generator in the Analysis ToolPak. -- Thanks, Shane Devenshire "usedtostata" wrote: Hi, I'm trying to figure out OLS regression with excel. Can anyone tell me why the data analysis toolpak gives me ANOVA results? Also, does anyone know an easy method for creating dummy varibles? Thanks |
#5
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regression analysis
Hey Jerry, Thanks for your reply.
About the dummies- basically if I want to recode categorical variables into a series of binary variables, how can I do that? Those aren't T-tests though. I thought T-tests were for testing the difference between two means (e.g. mean height for men vs means height for women). Cheers. "Jerry W. Lewis" wrote: The ANOVA table evaluates the significance of the model as a whole, vs. the t-tests below it in the output that evalute the significance of individual fitted coefficients. Can you be more specific about your dummy variable question? Jerry "usedtostata" wrote: Hi, I'm trying to figure out OLS regression with excel. Can anyone tell me why the data analysis toolpak gives me ANOVA results? Also, does anyone know an easy method for creating dummy varibles? Thanks |
#6
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regression analysis
usedtostata -
Also, does anyone know an easy method for creating dummy varibles? For a categorical variable with two values (e.g., male or female), I use one indicator variable, coded one or zero, indicating presence (e.g., 1 = male) or absence (e.g., 0 = not male) of that characteristic. For a categorical variable with k values, I use k-1 indicator variables, each coded one or zero. To create the one or zero data, I either (1) type the values in some of the cells and if there's a repeating pattern I copy large blocks or (2) use an IF function in each column if the one and zero values depend on values of an existing categorical variable. - Mike Middleton http://www.DecisionToolworks.com Decision Analysis Add-ins for Excel "usedtostata" wrote in message news Hi, I'm trying to figure out OLS regression with excel. Can anyone tell me why the data analysis toolpak gives me ANOVA results? Also, does anyone know an easy method for creating dummy varibles? Thanks |
#7
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regression analysis
'There are more t-tests, Horatio, than are dreamt of in your philosophy'
(apologies to Shakespeare) If a statistic is normally distributed, then that statistic divided by its estimated standard error follows the t distribution with degrees of freedom associated with the standard error estimate. In particular, if you have independent normally distributed errors, there is a t-test for each OLS regression coefficient. Those t-tests will rarely be independent of each other, since the coefficent estimates are usually correlated. Those t-tests are reported by the ATP regression tool, or can be constructed from LINEST by dividing a coefficient by its corresponding standard error (given in the 2nd line of LINEST output). Jerry "usedtostata" wrote: Hey Jerry, Thanks for your reply. About the dummies- basically if I want to recode categorical variables into a series of binary variables, how can I do that? Those aren't T-tests though. I thought T-tests were for testing the difference between two means (e.g. mean height for men vs means height for women). Cheers. "Jerry W. Lewis" wrote: The ANOVA table evaluates the significance of the model as a whole, vs. the t-tests below it in the output that evalute the significance of individual fitted coefficients. Can you be more specific about your dummy variable question? Jerry "usedtostata" wrote: Hi, I'm trying to figure out OLS regression with excel. Can anyone tell me why the data analysis toolpak gives me ANOVA results? Also, does anyone know an easy method for creating dummy varibles? Thanks |
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