Epidemiology & Biostatistics Test 4 questions
and answers with solutions 2025
hypothesis:
two or more population means are the same as each other
no difference - ANSWER null hypothesis
hypothesis:
not all of the population means are the same - ANSWER alternative hypothesis
primary inferential statistic of interest is - ANSWER the relationship / difference between two or
more unknown population means
- compare two means from two independent populations (independent sample comparisons)
- compare two means from the same population (related samples comparisons)
- the null is still the same no matter if it is between two independent or the same populations
Inferences from Two Independent Populations:
Want to compare means between exactly ___ samples drawn ____ ______ from two
independent populations (ex: drug vs. placebo groups in RCT drug trial) - ANSWER 2
at random
For two independent populations - ANSWER - samples MUST be randomly selected
- samples must come from populations that are observationally independent of each other
,If conditions are met (samples drawn at random and samples came from the populations
observationally independent of each other) we can proceed with appropriate inferential
analysis based on: - ANSWER - whether sample sizes are equal
- whether sample variances are equal
What is the easiest/most straight forward inference - ANSWER equal sample sizes / equal
variance
Equal sample sizes/equal variance
hypothesis:
population mean 1 = population mean 2
(two population means are the same) - ANSWER null hypothesis
Equal sample sizes/equal variance
hypothesis:
population mean 1 does NOT equal population mean 2
(2-tailed test) - ANSWER alternative hypothesis
Equal sample sizes/equal variance
hypothesis:
population mean 1 < or > population mean 2
(1-tailed test) - ANSWER alternative hypothesis
a statistical examination of two population means - ANSWER t-test
T value leads to the - ANSWER p-value
, the p value is based on the value of the - ANSWER t statistic
very large values of T statistics lead to: - ANSWER rejection of the null hypothesis
In order for T to be big, the numerator must be very ______. - ANSWER BIG
which would mean that the difference between the two means is very big
Larger the T value... - ANSWER the bigger the difference there is between the two sample
means
the smaller the P value leads to - ANSWER rejecting the null hypothesis
P values of the test estimates probability that the _______ hypothesis is true given the sample
results - ANSWER null
P-values < 0.05 generally lead to ______________ of the null
(95% confidence level) - ANSWER rejection
If you reject the null, the conclusion would be - ANSWER the two population means, as
estimated by their respective sample means, are NOT the same as each other
The _____________ could also be utilized as well, if such are reported/available to determine
acceptance/rejection of null - ANSWER confidence interval approach
Estimated 95% confidence intervals that don't include 0 lead to a ________ of the null -
ANSWER rejection
and answers with solutions 2025
hypothesis:
two or more population means are the same as each other
no difference - ANSWER null hypothesis
hypothesis:
not all of the population means are the same - ANSWER alternative hypothesis
primary inferential statistic of interest is - ANSWER the relationship / difference between two or
more unknown population means
- compare two means from two independent populations (independent sample comparisons)
- compare two means from the same population (related samples comparisons)
- the null is still the same no matter if it is between two independent or the same populations
Inferences from Two Independent Populations:
Want to compare means between exactly ___ samples drawn ____ ______ from two
independent populations (ex: drug vs. placebo groups in RCT drug trial) - ANSWER 2
at random
For two independent populations - ANSWER - samples MUST be randomly selected
- samples must come from populations that are observationally independent of each other
,If conditions are met (samples drawn at random and samples came from the populations
observationally independent of each other) we can proceed with appropriate inferential
analysis based on: - ANSWER - whether sample sizes are equal
- whether sample variances are equal
What is the easiest/most straight forward inference - ANSWER equal sample sizes / equal
variance
Equal sample sizes/equal variance
hypothesis:
population mean 1 = population mean 2
(two population means are the same) - ANSWER null hypothesis
Equal sample sizes/equal variance
hypothesis:
population mean 1 does NOT equal population mean 2
(2-tailed test) - ANSWER alternative hypothesis
Equal sample sizes/equal variance
hypothesis:
population mean 1 < or > population mean 2
(1-tailed test) - ANSWER alternative hypothesis
a statistical examination of two population means - ANSWER t-test
T value leads to the - ANSWER p-value
, the p value is based on the value of the - ANSWER t statistic
very large values of T statistics lead to: - ANSWER rejection of the null hypothesis
In order for T to be big, the numerator must be very ______. - ANSWER BIG
which would mean that the difference between the two means is very big
Larger the T value... - ANSWER the bigger the difference there is between the two sample
means
the smaller the P value leads to - ANSWER rejecting the null hypothesis
P values of the test estimates probability that the _______ hypothesis is true given the sample
results - ANSWER null
P-values < 0.05 generally lead to ______________ of the null
(95% confidence level) - ANSWER rejection
If you reject the null, the conclusion would be - ANSWER the two population means, as
estimated by their respective sample means, are NOT the same as each other
The _____________ could also be utilized as well, if such are reported/available to determine
acceptance/rejection of null - ANSWER confidence interval approach
Estimated 95% confidence intervals that don't include 0 lead to a ________ of the null -
ANSWER rejection
