Threats to Internal Validity

Question 1

What is chance?

Answer 1

Where we have the pressence of random error which is inherent in all measurement.

More error is not good

Question 2

How do we measure chance?

Answer 2

Using the p-value

Question 3

What is a P value?

Answer 3

Probability representing the strength of evidence to support hte null hypothesis

Question 4

What is a Large P value of >0.05 represent?

Answer 4

Supports the Null hypothesis hence their is no statistically significant difference between to two groups

Question 5

What is a samll p value of <0.05 represent?

Answer 5

We reject the null hypothesis hence there is a statistical significance between the two groups’ results

Question 6

What is the overall theme of what is the p value really saying?

Answer 6

The probability the results are due to chance rather than a real treatment effect

Question 7

How do we deal with chance?

Answer 7

Increase sample size
Recognize the extent via statistics and interpret the results accordingly

Question 8

What is important with respect to chance and statistical significance?

Answer 8

Does not necessarily mean clinical significance

Question 9

What is confounding?

Answer 9

When some factors other than the intervention or exposure under study, influence the overall outcome

Question 10

What are the ways we can help with confounding?

Answer 10

Randomization
Stratification
Matching

Question 11

What is randomization?

Answer 11

Ensures groups are similar in all aspects, known and unknown factors

Question 12

What is stratification?

Answer 12

Where we attempt to force an equal distribution of people from similar groups (Regina and Regina, Sask/Sask)W

Question 13

What is matching

Answer 13

Where we try and match people in the test/placebo group based on sex, age, and similar characteristics

Question 14

What is bias?

Answer 14

Problems with the way a study was designed conducted or analyzed that leads to incorrect results or conclusions

Question 15

What is selection bias?

Answer 15

Problems with how the study subject were selected

Question 16

What is information bias

Answer 16

Problems with measuing collecting or classifying information (Exposure and or outcomes)

Question 17

What does selection bias generally affect?

Answer 17

External validity

Question 18

Where do we see selection bias occur?

Answer 18

Self-seleciton/volunterr bias
Health workers bias
Attrition bias

Question 19

What are the two ways information bias can be categorized?

Answer 19

Outcome error
Exposure error

Question 20

What is outcome errors with respect to information bias?

Answer 20

RCT and observaiton studies where we have problems with measuring tools
Problems with actual measurements

Question 21

What is the exposure errors with respect to information bias

Answer 21

Problems with how subjects are categorized and problems with measuring tools

Question 22

What is an example of recall bias?

Answer 22

INdividuals remember things differentlu

Question 23

What is an example of interviewer bias?

Answer 23

Interviewers asks about exposure/outcome differently

Question 24

What is an example of surveillance/detection bias

Answer 24

One study group followed more closely than the other

Question 25

How do we deal with bias?

Answer 25

Recognize and acknowledge it

Standardization
Collect the same information form all subjects
blinding