Microsoft Office Tutorials and References
In Depth Information
If you took a basic algebra course in high school, you may remember the concept
of “absolute value.” In mathematical terms, the absolute value of any number is
always that number expressed as a positive number.
For example, the absolute value of 2.35 is
þ
2.35.
þ
2.35.
This becomes important when you are using the t-table in Appendix E of this
book. We will discuss this table later when we get to Step 5 of the one-group t-test
where we explain how to ﬁnd the critical value of t using Appendix E.
And the absolute value of minus 2.35 (i.e.
2.35 ) is also
4.1.4 STEP 4: Calculate the formula for the one-group t-test
Objective : To learn how to use the formula for the one-group t-test
The formula for the one-group t-test is as follows:
X
m
s X
t
¼
where
(4.1)
s
s
e
: ¼
S X ¼
p
n
(4.2)
:
This formula makes the following assumptions about the data (Foster, Stine, and
Waterman 1998): (1) The data are independent of each other (i.e., each person
receives only one score), (2) the population of the data is normally distributed, and
(3) the data have a constant variance (note that the standard deviation is the square
root of the variance).
To use this formula, you need to follow these steps:
1. Take the sample mean in your research study and subtract the population mean
m
from it (remember that the population mean for a study involving numerical
rating scales is the “middle” number in the scale).