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#1
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how to use multiple regression
Please can anyone help me solve this problem.
Use linest function to estimate what A,B,C & D will be, Compare them. Y= a+bx+cx^2+dx^3 assum x=0, x=1, .................. x= 100 Calculate the corresponding value of Y. Choose any coefficient for the constant. Thanks and regards, Dave |
#2
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how to use multiple regression
As written, your post is a little puzzling.
To use LINEST() you're going to need to start with both a series of X values and a series of Y values. So you won't "Calculate the corresponding value of Y," but you can use the regression coefficients and the constant to get estimates of Y. If what you're really after is the Y estimates, the TREND() function is more straightforward than LINEST() because it calculates the equation and applies it to your X values to return the Y estimates. But if you use LINEST(), and assuming you have Y in column A, X in column B, X^2 in column C and X^3 in column D, start by selecting a blank range four columns wide and five rows high, type this formula: =LINEST(A1:A100,B1:D100,,TRUE) and array-enter it with CTRL-SHIFT-ENTER instead of just ENTER. You can also square and cube X in the arguments: =LINEST(A1:A100,B1:B100^{1,2,3},,TRUE) What do you want to compare A,B,C & D to? Zero? Something else? Use the standard errors. You can force the constant to zero using LINEST's third argument but in general it's a bad idea. -- C^2 Conrad Carlberg Excel Sales Forecasting for Dummies, Wiley, 2005 "Dave in naigeria" <Dave in wrote in message ... Please can anyone help me solve this problem. Use linest function to estimate what A,B,C & D will be, Compare them. Y= a+bx+cx^2+dx^3 assum x=0, x=1, .................. x= 100 Calculate the corresponding value of Y. Choose any coefficient for the constant. Thanks and regards, Dave |
#3
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how to use multiple regression
Thanks Conrad.
The equation is actually not written well x^2 means x squared and x^3 means x cube.so the equation is Y= a + bx + cxsquared + dxcube "Conrad Carlberg" wrote: As written, your post is a little puzzling. To use LINEST() you're going to need to start with both a series of X values and a series of Y values. So you won't "Calculate the corresponding value of Y," but you can use the regression coefficients and the constant to get estimates of Y. If what you're really after is the Y estimates, the TREND() function is more straightforward than LINEST() because it calculates the equation and applies it to your X values to return the Y estimates. But if you use LINEST(), and assuming you have Y in column A, X in column B, X^2 in column C and X^3 in column D, start by selecting a blank range four columns wide and five rows high, type this formula: =LINEST(A1:A100,B1:D100,,TRUE) and array-enter it with CTRL-SHIFT-ENTER instead of just ENTER. You can also square and cube X in the arguments: =LINEST(A1:A100,B1:B100^{1,2,3},,TRUE) What do you want to compare A,B,C & D to? Zero? Something else? Use the standard errors. You can force the constant to zero using LINEST's third argument but in general it's a bad idea. -- C^2 Conrad Carlberg Excel Sales Forecasting for Dummies, Wiley, 2005 "Dave in naigeria" <Dave in wrote in message ... Please can anyone help me solve this problem. Use linest function to estimate what A,B,C & D will be, Compare them. Y= a+bx+cx^2+dx^3 assum x=0, x=1, .................. x= 100 Calculate the corresponding value of Y. Choose any coefficient for the constant. Thanks and regards, Dave |
#4
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how to use multiple regression
The equation is actually not written well x^2 means x squared and x^3 means
x cube.so the equation is Y= a + bx + cxsquared + dxcube That much was clear. -- C^2 Conrad Carlberg Excel Sales Forecasting for Dummies, Wiley, 2005 "Dave in naigeria" wrote in message ... Thanks Conrad. The equation is actually not written well x^2 means x squared and x^3 means x cube.so the equation is Y= a + bx + cxsquared + dxcube "Conrad Carlberg" wrote: As written, your post is a little puzzling. To use LINEST() you're going to need to start with both a series of X values and a series of Y values. So you won't "Calculate the corresponding value of Y," but you can use the regression coefficients and the constant to get estimates of Y. If what you're really after is the Y estimates, the TREND() function is more straightforward than LINEST() because it calculates the equation and applies it to your X values to return the Y estimates. But if you use LINEST(), and assuming you have Y in column A, X in column B, X^2 in column C and X^3 in column D, start by selecting a blank range four columns wide and five rows high, type this formula: =LINEST(A1:A100,B1:D100,,TRUE) and array-enter it with CTRL-SHIFT-ENTER instead of just ENTER. You can also square and cube X in the arguments: =LINEST(A1:A100,B1:B100^{1,2,3},,TRUE) What do you want to compare A,B,C & D to? Zero? Something else? Use the standard errors. You can force the constant to zero using LINEST's third argument but in general it's a bad idea. -- C^2 Conrad Carlberg Excel Sales Forecasting for Dummies, Wiley, 2005 "Dave in naigeria" <Dave in wrote in message ... Please can anyone help me solve this problem. Use linest function to estimate what A,B,C & D will be, Compare them. Y= a+bx+cx^2+dx^3 assum x=0, x=1, .................. x= 100 Calculate the corresponding value of Y. Choose any coefficient for the constant. Thanks and regards, Dave |
#5
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how to use multiple regression
Conrad already explained how to fit a cubic polynomial with LINEST. An
alternative to using the LINEST coefficients to predict y values at 1 to 100 would be =TREND(known_ys,known_xs^{1,2,3},ROW(A1:A100)) array entered. Jerry Dave in naigeria wrote: Please can anyone help me solve this problem. Use linest function to estimate what A,B,C & D will be, Compare them. Y= a+bx+cx^2+dx^3 assum x=0, x=1, .................. x= 100 Calculate the corresponding value of Y. Choose any coefficient for the constant. Thanks and regards, Dave |
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