Issues in Randomization Outline
Issues in Randomization Outline
Issues in Randomization Outline
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Vocabulary• Y i = β 0 + β 1 x 1i + ε i• Y = outcome or response variable– Might not be an actual response• X = covariate, variable• β 0 = <strong>in</strong>tercept– Average value of Y when X = 0• β 1 = slope, coefficient• ε = error, residual, difference betweensample fit or prediction and personY i = β 0 + β 1 x 1i + ε i• Subscript ‘i’ is person i; i = 15– Y 15 = 119 (SBP); x 15 = 1 (on treatment)• Y = β 0 + β 1 x 1 general sample model– Say β 0 = 150, β 1 = -20• Y 15 = β 0 + β 1 x 15 + ε 15– Thus 119 = 150 – 20*1 + ε 15– So ε 15 = 119 – 150 + 20 = -11– Difference between Y 15 and modelpredicted Y 15 = -11Vocabulary• Statistic: Compute from sample• Sampl<strong>in</strong>g Distribution– All possible values statistic can have– Samples of a given size randomly drawnfrom the same population• Parameter: Compute from population– Usually unknown to researcher– Several large studies <strong>in</strong> population26