Correlation and Multiple Regression

RUNNING HEAD: CORRELATION AND MULTIPLE REGRESSION
PSY-520 Graduate Statistics
Topic 5 – Benchmark – Correlation and Regression Project

Correlation and Multiple Regression
1. Mileage per gallon (mpg), weight, length, and engine displacement of engine of a car
have been considered as the four variables in this study.
a. Mileage for a car is believed to decrease with increase in weight, height, and
displacement of engine. Mileage per gallon is taken as the dependent and weight,
length, and engine displacement are taken as the independent variables. An inverse
and linear impact of the independent variables is expected on the dependent variable
of this study.
2. The primary data about the brand, mileage per gallon, weight, length, and engine
displacement of cars has been collected from 74 car owners. The car owners were
interviewed about their brand, model of car, and fuel efficiency. The interviewed car
owners belong to relatives, neighbors, or friends of the scholar. Initially, the scholar
collected data from 30 car owners, and then extended the sample size to 74 to ensure a
large sample (n > 30). After collecting primary data, the scholar collected information
about the weight, height, and displacement of engine from the brochure of the specific
brand and model of cars. This data is secondary in nature. The primary data is important
for the validity of the correct information on fuel efficiency. The scholar was looking at
R-square = 0.5 and the sample size is found to be sufficient for the chosen value (Faul,
Erdfelder, Buchner, & Lang, 2009).
a. The collected data has been included in a SPSS file for submission. Information about
the model of the cars has not been included in the sample data file.
3. The variables are continuous in nature and pairwise Pearson’s correlation coefficients
have been calculated in SPSS. “mpg” has significant and strong negative correlation with
the independent variables. Pairwise correlations between all the three independent
variables are statistically significant and strongly positive in nature. Table 1 presents the
specific values of the correlation coefficients.
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