Microsoft Office Tutorials and References
In Depth Information
6.9 End-of-Chapter Practice Problems
1. Suppose that you wanted to study the relationship between the number of
growth rings and the age of a Ponderosa pine tree (Pinus ponderosa). Is there a
relationship between these two variables? Let’s assume that you can measure
the growth rings that correspond to the number of years the tree has been
growing.
You have decided to use the age of the trees (in years) as the predictor, X, and
the number of growth rings as the criterion, Y. To test your Excel skills, you have
randomly chosen eight trees, and have recorded the hypothetical scores on these
variables in Fig. 6.30 :
Fig. 6.30
Worksheet data for Chap. 6: practice problem #1
Create an Excel spreadsheet and enter the data using AGE as the independent
variable (predictor) and NUMBER OF GROWTH RINGS as the dependent
variable (criterion).
Important note: When you are trying to find a correlation between two variables, it
is important that you place the predictor, X, ON THE LEFT
COLUMN in your Excel spreadsheet, and the criterion, Y,
IMMEDIATELY TO THE RIGHT OF THE X COLUMN. You
should do this every time that you want to use Excel to find a
correlation between two variables to check your thinking so that
you do not confuse these two variables with one another.
(a) Create the table using Excel, and then use Excel’s = correl function to find the
correlation between these two variables, and round off the result to two
decimal places. Label the correlation and place it beneath the table.
(b) Create an XY scatterplot of these two sets of data such that:
• Top
title:
RELATIONSHIP
BETWEEN
AGE
AND
NUMBER
OF
GROWTH RINGS IN PONDEROSA PINE TREES
• x-axis title: AGE (years)
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