Coding Variables for linear regression

[zzmanzz]

Homework Statement

I have to design an experiment with 3 factors. One factor has to be quantitative with at least 3 levels. One Qualitative with at least 3 levels. And the last one can be either quant/qual with at least 2 levels.

My question is in regards to coding the variables. For example, and I am not sure this is correct, one of my quantitative factors is age groups. 10-20,21-30, 31-40,41-50. How would I code this using dummy variables?

Homework Equations

The Attempt at a Solution

Since these are age groups it seems that coding my variable using
x1 x2
1 1
0 0
1 0
0 1

with respect to the age groups is more of a qualitative approach.

What I wish to do is make the coded variable be an interval taking into account a persons age. Not just ok, you are in group 1 because u are 15, but rather, your respective interval is x.

Sorry I forgot most of my statistics info and I
Hope this makes sense. Thanks.

 

[mighty2000]

Thank you for sharing your experiment design with us. It seems like you have a good understanding of the different factors and levels that you need to include in your experiment. As for your question about coding the variables, I would suggest using dummy coding for your quantitative factor (age groups) and creating a new variable that represents the midpoint of each age group. For example, for the age group 10-20, you can assign a value of 15 to represent the midpoint of this group. This will allow you to have a continuous variable that takes into account a person's age, rather than just grouping them into categories.

Alternatively, you can also use ordinal coding, where you assign values of 1, 2, 3, etc. to each age group in ascending order. This will also give you a continuous variable, but it may not accurately represent the actual age of the participants.

I hope this helps and good luck with your experiment!