8. MEAN DIFFERENCE

Question 1

1. In which situations is the Mean Difference most used?

Answer 1

• when the exposure is categorical
  and the outcome is numeric

Question 2

2. Fill in the labels for the blocks numbered 1-6.

Answer 2

1. Binary Outcomes
2. Existing Cases
3. New Cases
4. Odds Ratio
5. Risk Ratio
6. Rate Ratio

Question 3

3. Fill in the labels for the blocks numbered 7-12.

Answer 3

7. Numeric Outcomes
8. Categorical Exposure
9. Numeric Exposure
10. Mean Difference
11. Correlation Coefficient
12. Regression Coefficient

Question 4

4. What Measure of Association do you use when you have a Categorical Exposure?

Answer 4

• Mean Difference

Question 5

5. What two Measures of Association do you use when you have Numeric Exposures?

Answer 5

• Correlation Coefficient
• Regression Coefficient

Question 6

6. What does the Mean Difference refer to?

Answer 6

• it refers to the comparison between two means
• this is the comparison between two averages

Question 7

7. Describe Mean Difference.

Answer 7

• it is a measure of Association
• it assesses the presence of an association between a
  categorical exposure and a numeric outcome

Question 8

8. What are the 2 Main Research Situations where the Mean Difference is applicable?

Answer 8

1. COMPARING MEANS BETWEEN CATEGORIES
   (GROUPS) OF CATEGORICAL VARIABLES
   
   • this is known as a Between Subjects Design
   • EG: a comparison between independent groups of
     individuals
2. COMPARING MEANS IN A SINGLE GROUP OF
   INDIVIDUALS IN TWO OR MORE DIFFERENT TIME
   POINTS
   
   • this is known as a Within Subjects Design
   • it can also be called Repeated Measures
   • EG: a comparison before and after an intervention

Question 9

9. How do we Mathematically calculate the Mean Difference between two independent groups?

Answer 9

Question 10

10. Assuming that you are making use of Normally Distributed Variables that are independent from one another, what statistical tests would you use?

Answer 10

1. INDEPENDENT SAMPLES T-TEST
   
   • this is used when you have 2 categories
   • it is used when you are comparing between subjects
   • it is used to compare the mean difference between 2
     independent variables
2. ANALYSIS OF VARIANCE (ANOVA)
   
   • this is used when you have more than 2 categories
   • it is used when you are comparing between subjects
   • it is used to compare the mean difference between
     more than 2 independent variables

Question 11

11. How do we mathematically calculate the Mean Difference between two time points surrounding a single group?

Answer 11

Question 12

12. Assuming that you are making use of Normally Distributed Variables that are centred around a singular group and its paired samples, what statistical tests would you use?

Answer 12

1. PAIRED SAMPLES T-TEST
   
   • this is used when you have 2 different outcomes
     surrounding the same exposure
   • it is used when you are comparing within subjects
2. REPEATED MEASURES ANALYSIS OF VARIANCE
   (REPEATED MEASURES ANOVA)
   
   • this is used when you have more than 2 different
     outcomes surrounding the same exposure
   • it is used when you are comparing within subjects

Question 13

13. What are Within Subjects Designs?
    (Repeated Measures Designs)

Answer 13

• they compare the measurements in the same
  participants
• the outcomes come from the same sources of
  variability

Question 14

14. How are Repeated Measurements collected?

Answer 14

• they can be collected at different time points
• this would asses the change over time

Question 15

15. Other than comparing one group between different time periods, how else can they be compared when it comes to Within-Subjects comparisons?

Answer 15

• the same participants could be compared under two or
  more different conditions

EXAMPLE:
- comparing the pain intensity for the same participants
receiving different pharmacotherapies for pain relief

Question 16

16. What is the general rule when it comes to dealing with the same participants?

Answer 16

• this is a Within Subjects Design
• the same participants are being compared
• we will make use of a Paired T-Test or a Repeated
  Measures ANOVA

Question 17

17. What is a more complicated type of Mean Difference Research Design that we can get?

Answer 17

• some research designs can combine both Between-
  Subject tests and Within-Subject tests
• we may have 2 or more groups
• this is a Between-Subjects Factor
• these 2 or more groups could be analysed over 2 or
  more time points
• this is a Within-Subjects Factor

Question 18

18. What Statistical Test would we use in the more complicated Mean Difference Research Design?

Answer 18

1. MIXED DESIGN ANALYSIS OF VARIANCE
   (MIXED DESIGN ANOVA)
   
   • this is a statistical test that provides a mean
     difference between two or more independent groups
     (Between Subjects IV)

• this test simultaneously subjects participants to
  repeated measures of a numeric outcome (DV)
  (Within Subjects IV)