unit 6 additional answers

unit 6 additional answers - Unit 6...

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Click to edit Master subtitle style Unit 6 Questions and Answers
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Study guide for Unit 6: Precision/validity of an association Internal vs. external validity Generalizability Chance: population vs. samples Hypothesis testing ( p -values to reject or accept Ho) Estimation: Confidence intervals (95%, 99%) Computation and interpretation of a 95% confidence interval Statistical power: review of Type I and Type II errors Four features to power Example of a sample size and power calculation Overpowered samples: clinical vs. statistical significance
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What are the 4 explanations for an association to be obser ved in a 1 – 2 – 3 – 4 -
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What are the 4 explanations for an association to be observed in a study? n 1 – Chance = PRECISION n 2 – Bias - confounding n 3 – Bias - other n 4 – Truth (causal) We must rule out 1-3 and then infer 4 through causal criteria that we will learn more about in Segment 3 of the VALID ITY
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Define validity and name and Validity: Two types of validity: 1 – 2 -
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Define the 2 types of validity n Validity: The extent to which what we measure in the study is TRUE in the real world. n Two types of validity: 1 – Internal validity: the extent to which the comparison between the two groups (cases/controls; exposed/unexposed) is FAIR and the results are a true representation of the real measure of effect (OR/RR/AR) 2 – External validity: the extent to which study data
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Tr ue or False? External validity must be sought first before internal validity T F
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True or False? n External validity must be sought first before internal validity T F n Internal validity is most important. When we are sure that a finding is internally valid, we can ask whether it is externally valid. If it is not, it can still stand as a valid study. n Ideally we will design our study to have both types
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I nternal vs. exter nal validity {7418B5D8-F7CD-4DB4-8F48-EBEDB BE0B09} Sample {6DEF3 9C-A13C-4696-9479-2 1032DF97DE} Target population {8BD9C68A-D06C-42CF-846B-52E 321CD8D6} State/country/world Extent to which the  cases/controls or  exposed/unexposed  come from the  same underlying  Extent to which the  cases/controls or  exposed/unexposed  represent all cases/ controls and all 
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Chance = precision Is our finding due to chance? Each sample will have some natural variability Each ‘study’ draws a new sample A case-control study attempts to draw a sample from the universe of cases and ‘non-cases’ in the population
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Calculate the OR for each scenario and label each as ‘Type 150 100 175 75 D Ð E Ē 200 50 200 50 D Ð E Ē 125 125 125 125 D Ð E Ē 125 125 175 75 D Ð E Ē “TRUE TABLE”
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unit 6 additional answers - Unit 6...

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