You are considering developing a regression equation relating a dependent variable to two independent variables. One of the vari
ables can be measured on a ratio scale, but the other is a categorical variable with two possible levels. a. How many dummy variables are needed to represent the categorical variable?
b. Write the multiple regression equation relating the dependent variable to the independent variables.
c. Interpret the meaning of the coefficients in the regression equation.
imagine a circle. its center is A, and it goes through B, so its radius is AB.
then it is important to know that the sum of all the angles in a triangle is 180 degrees.
one angle (at C) is 90. the angle at B is 25. so, the angle at A is 180 - 90 - 25 = 65 degrees.
more back to our circle.
in this circle the line CB is the sine of the angle at A multiplied by the radius.
and AC is the cosine of the angle at A multiplied by the radius.
we can ignore the orientation + and - of these functions, as we are only interested in the absolute length (and we can mirror the triangle, and all the angles and side lengths still stay the same).
=> CB = sin(A)×AB
AC = cos(A)×AB
=> 5 = sin(65)×AB
=> AB = 5 / sin(65)
=> AC = cos(65)×5/sin(65) = 5 × (cos(65)/sin(65)) =