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Biostats Module 1 and 4
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Terms in this set (15)
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
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