Week 6- Introduction to Evidence

Question 1

What is a correlation?

Answer 1

Technique for investigating the relationship between two numerical values

Question 2

What is a correlation coefficient?

Answer 2

Measurement of the relationship between two numerical variables/measurements

Question 3

What is a positive correlation?

Answer 3

High values in one variable are associated with high values of another variable

Question 4

What is a negative correlation?

Answer 4

High values on one variable are associated with low values of another variable

Question 5

How do you measure the strength of the correlation?

Answer 5

Close to 1 or -1: strong relationship

Question 6

Describe the Pearson correlation coefficient

Answer 6

• Measures strength of linear association between 2 quantitative variables
• Below 0= negative correlation
• Above 0= positive correlation
• Sample size above 30

Question 7

Describe the Spearman correlation coefficient

Answer 7

• Measures strength of association between two ranked variables
• Sample size small (below 30)

Question 8

What is the difference between parametric and non parametric data?

Answer 8

Parametric: assumes normal distribution, draws more conclusions from sample to population
Non-Parametric: no assumption on distribution, simple and less effected by outliers

Question 9

What is a hierarchy of evidence?

Answer 9

• Ranking system, ranks quality of research
• What study design provides most robust evidence
• Based in rigour and ability to minimise bias
• Understanding ability of studies to minimise bias

Question 10

What is the purpose of hierarchy of evidence?

Answer 10

• Helps to be a discerning consumer of research (can I trust research?)
• Some research designs better at reducing chance, minimising bias, control confounders
• Choose best evidence to answer question

Question 11

What are examples of reporting bias?

Answer 11

• Publication Bias
• Location Bias
• Language Bias

Question 12

What is publication bias?

Answer 12

Selection of research evidence due to positive findings published in some areas

Question 13

What is location bias?

Answer 13

Only selecting research evidence from one source

Question 14

What is language bias?

Answer 14

Selecting research evidence from you native language

Question 15

What are examples of methodological bias?

Answer 15

• Sampling Bias
• Allocation Bias
• Maturation Bias
• Attrition Bias
• Measurement Bias
• Placebo
• Hawthorne Effect

Question 16

What is sampling bias?

Answer 16

• Who gets selected for study and who gets left out

- Sample should represent wider population

Question 17

What is allocation bias?

Answer 17

Who gets into intervention group and who gets into control group

Question 18

What is maturation bias?

Answer 18

Change which occur naturally over time

Question 19

What is attrition bias?

Answer 19

Who drops out from the study; how this can change sample and effect results

Question 20

What is measurement bias?

Answer 20

• Errors in measuring data/variables
• Lack of reliable and valid tools
• Expectations of researcher/health professionals

Question 21

What is a placebo?

Answer 21

Participants believe that intervention will result in improvement

Question 22

What is the hawthorne effect?

Answer 22

Participants experience changes due to attention given to them as part of research

Question 23

Of all hierarchies of evidence, which is the best?

Answer 23

• NHMRC for Australia
• No universal agreement
• Point of difference is inclusion/exclusion of expert opinion