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A00-240 Exam - Question 9


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A linear model has the following characteristics:

"¢ A dependent variable (y)

"¢ One continuous variable (x1)

"¢ One categorical (Ñ1 with 3 levels) predictor variable and an interaction term (Ñ1 by x1)

How many parameters, including the intercept, will be estimated for this model?

Enter your numeric answer in the space below.

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Correct Answer:

To determine the number of parameters in a linear model with the given characteristics, we need to account for each component: the intercept, the continuous variable, the categorical variable with 3 levels, and the interaction term. The intercept contributes 1 parameter. The continuous variable (x1) contributes 1 parameter. The categorical variable with 3 levels contributes 2 parameters (since we need k-1 parameters for k levels). The interaction term (Ñ1 by x1) between the categorical variable (Ñ1 with 3 levels) and the continuous variable (x1) contributes 2 parameters (one for each interaction level). Adding these together, we have 1 (intercept) + 1 (x1) + 2 (Ñ1) + 2 (interaction) = 6 parameters to be estimated.

Discussion

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Unorich
Oct 7, 2020

I think this is wrong. Original question had a "quadratic" variable and this question excludes it and should be 6, not 7

chuck
Mar 23, 2021

intercept = 1 "¢ A dependent variable (y) = 1 "¢ One continuous variable (x1) = 1 "¢ One categorical (Ñ1 with 3 levels) predictor variable = 2 interaction term (Ñ1 by x1) = 2 Total of 7 parameters

Krishna1985
Nov 16, 2020

I also think that it is 6