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BIO 550 Exam 3 Questions

Terms in this set (24)

The __ __ is a continuous probability distribution describing a bell-shaped curve. It is a good approximation to the frequency distributions of many biological variables.
normal distribution
A __-__ is the probability of obtaining data (or data showing as great or greater difference from the null hypothesis) if the null hypothesis were true.
p-value
For a variable with normal distribution, about __ of values within one standard deviation of the mean and about __ are within two standard deviations of the mean.
two-thirds, 95%
The __ __ __ is a normal distribution with a mean of zero and a standard deviation of one
standard normal distribution
A __ __ __ tells us how many standard deviations a particular value is from the mean.
standard normal deviate
True or False: If a variable has a normal distribution in a population, then the distribution of sample means is also normal.
True
According to the __ __ __, the sum or mean of a large number of measurements randomly sampled from a non-normal population is approximately normally distributed.
central limit theorem
True or False: If a variable has a normal distribution, its mean and median are the same, but the mode is equivalent to the standard deviation.
False
To describe a normal distribution, we need to know the __ and the __.
mean, standard deviation
The difference between the sample mean and the true mean divided by the estimated standard error has a Student's __ with n-1 degrees of freedom
t-distribution
Using the equation sheet from exam 3, which equation is used to calculate the 95% confidence intervals of the mean in a Student's t-distribution?
average mean plus or minus t at a particular critical value given degrees of freedom
In a one-sample t-test, the null hypothesis is that the true mean is equal to __.
the true mean
The __ __ t-test compares the mean of a random sample from a normal population with the population mean proposed in a null hypothesis.
one-sample
The two assumptions of the one-sample t-test are:
1) The data are a __ sample from the population.
2) The variable is __ distributed in the population.
randomly, normally
In a __ design, both treatments are applied to every sampled unit.
paired
In a __ design, each treatment group is composed of an independent, random sample of units
two-sample
True or False: Paired measurements are converted to a single measurement by dividing them.
False
The two assumptions of paired t-tests are:
1) The sampling units are __ sampled from the population
2) The paired differences have a __ distribution in the population
randomly, normally
True or False: Paired t-tests make no assumptions about the distribution of individual units in a sampling unit
True
The __ is the average of the variances of the samples weighted by their degrees of freedom
pooled sample variance
In a two-sample t-test, the null hypothesis is that the mean of the population is equal to __
the mean of the other population
The assumptions of a two-sided t-test are:
1) Each of the two samples is a __ sample from its population
2) The numerical variable is __ distributed in each population
3) The __ of the numerical variable is the same in both populations
random, normally, standard deviation
__ t-test compares the means of two groups and can be used even when the standard deviations of the two groups are not equal
Welch's
The __ states that comparisons between two groups should always be made directly, not indirectly by comparing both to the same null hypothesized value.
fallacy of indirect comparison
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