one way annova
SPSS Basics for One-way ANOVA
As an illustration of the process, consider the data given in Example 11-8, pp. 593 – 595, of Bluman’s Elementary Statistics: A Brief Version.
Problem Statement: A researcher wishes to try three different techniques to lower the blood pressure of individuals diagnosed with high blood pressure. The subjects are randomly assigned to three groups; the first group takes medication, the second group exercises, and the third group follows a special diet. After four weeks, the reduction in each person’s blood pressure is recorded. At α = 0.05 , test the claim that there is no difference among the means. The data are:
Medication Exercise Diet
10
6
5
12
8
9
9
3
12
15
0
8
13
2
4
Defining Variables and Entering the Data
Begin by defining the variables in an SPSS Data file in the Variable View window of the
SPSS Data Editor; be sure to safe the data file and the resulting output file. Here’s how this might be done.
First name the variables; let “Bp” represent the variable for blood pressure and “Tr” the categorical variable for treatment method. Note that even though “Tr” is categorical, it is assigned numerical (integer) values. SPSS will interpret these values as identifying which group each value of “Bp” belongs to. For both variables, set the number of decimal places to be zero. Next, give each variable a (short) label, and finally assign labels to each value of “Tr”, as shown below.
The Variable View window of the SPSS Data Editor should have the appearance shown below. Prepared by: Chris Hay-Jahans, UAS Mathematics Program
Page 1 of 8
SPSS Basics for One-way ANOVA
Switch the data editor to the Data View window and enter the data as shown below. Be sure to save the file as soon as you are done.
Performing the One-Way ANOVA F-test
The hypotheses to be tested are
H 0 : μ1 = μ 2 = μ 3
(Claim)
H 1 : At least one mean is different from the others
Prepared
As an illustration of the process, consider the data given in Example 11-8, pp. 593 – 595, of Bluman’s Elementary Statistics: A Brief Version.
Problem Statement: A researcher wishes to try three different techniques to lower the blood pressure of individuals diagnosed with high blood pressure. The subjects are randomly assigned to three groups; the first group takes medication, the second group exercises, and the third group follows a special diet. After four weeks, the reduction in each person’s blood pressure is recorded. At α = 0.05 , test the claim that there is no difference among the means. The data are:
Medication Exercise Diet
10
6
5
12
8
9
9
3
12
15
0
8
13
2
4
Defining Variables and Entering the Data
Begin by defining the variables in an SPSS Data file in the Variable View window of the
SPSS Data Editor; be sure to safe the data file and the resulting output file. Here’s how this might be done.
First name the variables; let “Bp” represent the variable for blood pressure and “Tr” the categorical variable for treatment method. Note that even though “Tr” is categorical, it is assigned numerical (integer) values. SPSS will interpret these values as identifying which group each value of “Bp” belongs to. For both variables, set the number of decimal places to be zero. Next, give each variable a (short) label, and finally assign labels to each value of “Tr”, as shown below.
The Variable View window of the SPSS Data Editor should have the appearance shown below. Prepared by: Chris Hay-Jahans, UAS Mathematics Program
Page 1 of 8
SPSS Basics for One-way ANOVA
Switch the data editor to the Data View window and enter the data as shown below. Be sure to save the file as soon as you are done.
Performing the One-Way ANOVA F-test
The hypotheses to be tested are
H 0 : μ1 = μ 2 = μ 3
(Claim)
H 1 : At least one mean is different from the others
Prepared