Lec 78: Evidence-Appraisal: Hypothesis testing

Question 1

What are the paired study designs?

Answer 1

Pre-post comparison study
Cross-over study
Matched case-control study
Twin study

Question 2

What are the unpaired study designs?

Answer 2

Traditional randomized control trial

Epidemiology studies without matching

Question 3

Describe pre-post comparison study

Answer 3

• Single intervention

* Each pt observed before and after intervention (same person measured twice)

Question 4

Describe cross-over study

Answer 4

• Each person receives sequence of interventions
• Pt randomized to sequence of interventions
• Advantages: good for short and/or acute treatments and treatments measuring palliation not cure
• Limitations: not feasible for certain outcomes/treatments (i.e. deaths)

Question 5

Describe matched case-control study

Answer 5

Identify study participants then match with similar control participants

Question 6

Describe twin study

Answer 6

Can be used to distinguish between genetics and environment

Question 7

Provide fundamental concepts of hypothesis testing

Answer 7

Hypothesis tests: Estimate the probability of obtaining the observed result, or one more extreme, if there is no true difference. Use info to make decisions about the population

• Process for choosing between competing hypotheses
• One-sided test: greater than or less than for null and alternative hypotheses
• Two-sided test: equal and does not equal for null and alternative hypotheses
• Compare P-value (determined from test statistic) to alpha to determine statistical significance

•General form
Test statistic = (observed value - hypothesized value) / Std Error of observed value

Question 8

Provide fundamental concepts of confidence intervals

Answer 8

Confidence intervals: Estimate a range of values that is likely to include the true (population) value

•Provides range of plausible values

•General form
CI = estimate plus/minus critical value X standard error

Question 9

How are clinical and statistical significance different

Answer 9

Statistical significance provides the answer to a hypothesis test which removes chance from a study

Clinical significance considers the statistical significance and other factors in order to determine if a study is relevant