5 - External Validity

Question 1

what is internal vs external validity?

Answer 1

internal: the ability of the study results to support a cause-effect relationship btw the treatment and observed outcome
external: the applicability of the study results to patients

Question 2

what is efficacy vs effectiveness?

Answer 2

• both wrt external validity!
• efficacy (aka explanatory/management): can intervention work under “ideal” circumstances?
• effectiveness (aka pragmatic): does the intervention work under “usual” circumstances?
• typically most trials will have both, but more efficacy

Question 3

what are the 8 hierarchies within valid studies?

Answer 3

• participant eligibility criteria
• intervention flexibility
• practitioner expertise
• follow-up intensity
• nature of outcomes
• participant compliance
• practitioner adherence
• primary analysis

Question 4

participant eligibility criteria

Answer 4

• p 66

Question 5

intervention flexibility

Answer 5

• p 66

Question 6

practitioner expertise

Answer 6

• p 66

Question 7

follow-up intensity

Answer 7

• p 66

Question 8

nature of outcomes

Answer 8

• p 67

Question 9

participant compliance

Answer 9

• p 67

Question 10

practitioner adherence

Answer 10

• p 67

Question 11

primary analysis

Answer 11

• p 67

Question 12

a statistically non-singificant result in a pragmatic trial can be interpreted as….

Answer 12

• either there is no diff btw the groups (signal is too small)
• or the variability in the outcome is too great to detect diff (noise too big)

Question 13

if a well designed and executed efficacy study shows that the experimental treatment is no better than the control, we can conclude that..

Answer 13

• there is no diff btw treatment groups
• bc efficacy study has done all it can to reduce noise, so if we still cannot detect signal in this case, we know signal is not there (not big)