15 terms

Probability Distributions

describe the probability of events and the range of the variable

cross-sectional studies

aimed at finding out the prevalence of a problem by taking a snapshot of a populations; measures the change in a situation

retrospective studies

investigate an issue that has occurred in the past ; involves secondary data collection or from previous studies

power

1 - p(type 2 error) or 1 - beta ; probability of finding a true difference;

effect size

how effective we think our treatment is; minimum deviation from null hypothesis that you hope to detect; difference between the two arms of the study; take mean differences of two groups/SD of one of the groups

smaller alpha

less type 1 error; accounts for less of type 1 error

Beta

probability of accepting null hypothesis even though it is false;

sampling affects

margin of error and type 2 error

left skewed

mean < median < mode

right skewed

mode<median<mean

Sum of squares

(x-mean)^2 + ...

sample variance

((x-mean)^2 + ... divided by n) - 1

standard deviation

square root(variance)

coefficient of variation

SD/mean; summarizes the amount of variation as a percentage or proportion of total

standard error of mean

SD/ sqrt(n) ; how much mean deviates from parametric mean ; measures accuracy of which sample mean represents the population