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Biostats Midterm #2

Terms in this set (14)

The t distribution differs from a ___ distribution when sample sizes are small. However, as sample size gets really large the t distribution converges on the ___ distribution.
normal
In class, we discussed one-way ANOVA as a comparison of signal and noise. In this analogy, the "noise" is embodied by
the within-group component of variance and the mean squares for the error term
Which answer(s) best describes the null hypothesis for a one-way ANOVA?
the true, among-group variance is zero & the means of all groups are the same
Which of the following changes will decrease Type II error rates?
an increase in sample size & an increase in effect size
Which of the following changes will decrease Type I error rates?
...
The chi-squared distribution is used in which of the following?
1. calculating confidence intervals for estimates of variances
2. goodness of fit test
3. test of independence
Experimental studies strive to reduce bias and/or increase precision. Identify which of these two goals is aided by the following procedures

1. comparing the recovery of patients who are administered a drug with patients who are administered a placebo
reducing bias
using a random number generator to assign subjects to treatments
reducing bias
taking as many samples as time and money allow
increasing precision
it helps to think of statistical tests of comparisons of whether the "signal" in your data is large relative to the "noise". in a two-sample t test, the signal is embodied by
the difference in means
Past research suggests that French wine is more popular. You could test whether the odds ratio of a customer choosing French over German wine was significantly greater than 1, but would this be a 1-tailed or 2-tailed test? For additional practice, do this test
one-tailed
suppose you wanted to test whether the type of wine purchased was independent of the nationality of the music playing. what type of test would you use?
chi-squared test
hypothesis testing involves calculating the probability of observing a particular sample of data, if the null hypothesis is true. a critical value of a test statistic is determined by ___, and if our test statistic is more extreme than ___ we ___ the null hypothesis
alpha, the critical value, reject
The t distribution differs from a ___ distribution when sample sizes are small. However, as sample size gets really large the t distribution converges on the ___ distribution.
normal
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