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Lecture and Examples
Topic 6: Models with a Single Quantitative
Independent Variable
As described in previous lectures, the first step in the
construction of a regression model is to hypothesize the
deterministic portion of the probabilistic model.
So far,
we assume that we know the deterministic portion of our
probabilistic model.
However, in a model building
process, we do not know the best model in advance.
We
need to fit several models before we can identify the
model that fits the data best.
In this lecture, we will
discuss the model building process with one quantitative
independent variable.
Quantitative variables
always
assume numerical values whereas
qualitative variables
usually assume nonnumerical values.
The possible values
of an independent variable are called
levels
.
Each level of
a
Quantitative Independent Variable
usually assumes
numerical value and each level of a
Qualitative
Independent Variable
usually assumes nonnumerical
value.
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View Full DocumentExample 12.11
:
For each of the following independent variables, identify
the variables as quantitative or qualitative.
(a) Number of years experience
(b) Gender of the employee
(c) Rank of the employee
(d) Weight
(e) Height
(f) Volume
(g) Annual Household Income
(h) Letter Grade
Solution:
•
Quantitative independent Variables
: Number of
years experience, Weight, Height, Volume, and Annual
Household Income
•
Qualitative Independent Variables
: Gender of the
employee, Rank of the employee, and Letter Grade
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 Spring '08
 Staff

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