Worksheet #1: T-tests

INDEPENDENT SAMPLES: An exercise physiologist is interested in examining the effect of a diabetes education intervention (designed to teach parents about healthy eating and physical activity) on the number of diabetes diagnoses that occur within the following year in a sample of pre-diabetic children.A total of 12 families with pre-diabetic children are recruited.Six families were in the diabetes education group and 6 were in the control group.The number of diagnoses for each family are recorded in the Table below.

Family

Group

# of diagnoses in year 1

1

Diabetes education

10

2

Diabetes education

8

3

Diabetes education

5

4

Diabetes education

4

5

Diabetes education

6

6

Diabetes education

10

7

Control

7

8

Control

8

9

Control

9

10

Control

6

11

Control

5

12

Control

9

1. What is your null hypothesis for this research question?

THERE IS NO DIFFERENCE FOR DIABETES EDUCATIONAL INTERVENTION WITH THE NUMBER OF FAMILIES RECEIVING DIAGNOSIS BETWEEN YEAR 1 AND 2.

1. Using an independent samples t-test, calculate the observed t-statistic from the data above in Excel.Hint: You'll need to calculate the mean and sum of squares for each group.

1. What is the critical t-value for this research question?Hint: Use the table of critical values and the degrees of freedom to locate this value.The alpha = 0.05.
2. What can you conclude based on your data?Do you reject or fail to reject the null hypothesis?

DEPENDENT SAMPLES: Using the same groups as above, the researcher continues the intervention for a second year and wants to know if the number of diagnoses varies between year 1 and year 2.Only the 6 families receiving the intervention are followed.The number of diagnoses for each family are recorded in the Table below.

Family

Group

# of diagnoses in year 1

# of diagnoses in year 2

1

Diabetes education

10

6

2

Diabetes education

8

5

3

Diabetes education

5

6

4

Diabetes education

4

4

5

Diabetes education

6

2

6

Diabetes education

10

3

1. What is your null hypothesis for this research question?

THERE IS NO DIFFERENCE FOR DIABETES EDUCATIONAL INTERVENTION

1. Using an dependent samples t-test, calculate the observed t-statistic from the data above in Excel.Hint: You'll need to calculate the sum of differences and the sum of squared differences for each group.
2. What is the critical t-value for this research question?Hint: Use the table of critical values and the degrees of freedom to locate this value.The alpha = 0.05.
3. What can you conclude based on your data?Do you reject or fail to reject the null hypothesis?