Biostatistics exam 3 questions with
complete solutions A+ rated
T/F Two samples will probably have different means even if they are both the same size and they are
both selected from the same population? - correct answer ✔✔True
A researcher selects a sample and administers a treatment to the individuals in the sample. If the sample
is used for a hypothesis test, what does the null hypothesis (Ho) says about the treatment? - correct
answer ✔✔the treatment has no effect on the scores
if a hypothesis test produces a z score in the critical region, what decision should be made? - correct
answer ✔✔reject the null hypothesis
accurately describe a hypothesis test - correct answer ✔✔an inferential technique that uses that data
from a sample to draw inferences about a population
accurately describe the critical region - correct answer ✔✔outcomes with very low probability if the null
hypothesis is true
a sample of n=25 individuals is selected from a population with u=70, and a treatment is administered to
the sample. What is expected if the treatment actually has no effect? - correct answer ✔✔the sample
mean should be close to 70 and should lead you to fail to reject the null hypothesis
what is an accurate definition of a type 1 error? - correct answer ✔✔rejecting a true null hypothesis
the critical boundaries for a hypothesis test are z= +/- 1.96 . If the z score for the sample data is z = +/-
1.89, what should be done? - correct answer ✔✔fail to reject the null hypothesis (Ho)
what is the first step in a hypothesis test - correct answer ✔✔state your hypotheses
, what is the second step in the hypothesis test - correct answer ✔✔set your decision criteria
what is the third step in the hypothesis test - correct answer ✔✔collect data and calculate
what is the fourth step in the hypothesis test - correct answer ✔✔make a decision based on your results
under what circumstances can a very small treatment effect still be significant - correct answer ✔✔if the
sample size (n) is very large
what is an accurate definition form the power of a statistical test? - correct answer ✔✔the probability of
rejecting a false null hypothesis
what will increase the power of a statistical test - correct answer ✔✔changing the sample size from n=20
to n=100
when n is small (less than 30), how does the shape of the t distribution compare to the normal
distribution? - correct answer ✔✔it is flatter and more spread out than the normal distribution
on average, what value is expected for the t statistic when the null hypothesis is true - correct answer
✔✔0
if two samples are selected from the same population, under what circumstances will the two samples
have exactly the same t statistic? - correct answer ✔✔if the samples are the same size and they have the
same mean and the same variance
(solve) a sample of n=9 scores has a variance = 36. what is the estimated standard error for the sample? -
correct answer ✔✔Sm= √(variance/n) = 2
(solve) a researcher conducts a hypothesis test using a sample from an unknown population. If the t
statistic has df=30, how many individuals were in the sample? - correct answer ✔✔{df= n-1 } >>> n=31
complete solutions A+ rated
T/F Two samples will probably have different means even if they are both the same size and they are
both selected from the same population? - correct answer ✔✔True
A researcher selects a sample and administers a treatment to the individuals in the sample. If the sample
is used for a hypothesis test, what does the null hypothesis (Ho) says about the treatment? - correct
answer ✔✔the treatment has no effect on the scores
if a hypothesis test produces a z score in the critical region, what decision should be made? - correct
answer ✔✔reject the null hypothesis
accurately describe a hypothesis test - correct answer ✔✔an inferential technique that uses that data
from a sample to draw inferences about a population
accurately describe the critical region - correct answer ✔✔outcomes with very low probability if the null
hypothesis is true
a sample of n=25 individuals is selected from a population with u=70, and a treatment is administered to
the sample. What is expected if the treatment actually has no effect? - correct answer ✔✔the sample
mean should be close to 70 and should lead you to fail to reject the null hypothesis
what is an accurate definition of a type 1 error? - correct answer ✔✔rejecting a true null hypothesis
the critical boundaries for a hypothesis test are z= +/- 1.96 . If the z score for the sample data is z = +/-
1.89, what should be done? - correct answer ✔✔fail to reject the null hypothesis (Ho)
what is the first step in a hypothesis test - correct answer ✔✔state your hypotheses
, what is the second step in the hypothesis test - correct answer ✔✔set your decision criteria
what is the third step in the hypothesis test - correct answer ✔✔collect data and calculate
what is the fourth step in the hypothesis test - correct answer ✔✔make a decision based on your results
under what circumstances can a very small treatment effect still be significant - correct answer ✔✔if the
sample size (n) is very large
what is an accurate definition form the power of a statistical test? - correct answer ✔✔the probability of
rejecting a false null hypothesis
what will increase the power of a statistical test - correct answer ✔✔changing the sample size from n=20
to n=100
when n is small (less than 30), how does the shape of the t distribution compare to the normal
distribution? - correct answer ✔✔it is flatter and more spread out than the normal distribution
on average, what value is expected for the t statistic when the null hypothesis is true - correct answer
✔✔0
if two samples are selected from the same population, under what circumstances will the two samples
have exactly the same t statistic? - correct answer ✔✔if the samples are the same size and they have the
same mean and the same variance
(solve) a sample of n=9 scores has a variance = 36. what is the estimated standard error for the sample? -
correct answer ✔✔Sm= √(variance/n) = 2
(solve) a researcher conducts a hypothesis test using a sample from an unknown population. If the t
statistic has df=30, how many individuals were in the sample? - correct answer ✔✔{df= n-1 } >>> n=31
