4.1
True or False: Association doesn't imply causation
a -- of n subjects from a population is
one in which each possible sample of that size has the
same chance of being selected.
a simple random sample
When we use a....it allows the researcher to analyze the effectiveness of the primary treatment.
control comparison group
This experiment uses a single experiment to analyze the effects of 2 or more explanatory variables on the response variable
Multifactor Experiment
Assigning subjects to a certain experimental condition and then observing outcomes on the response variable is what kind of study?
Experiment
Research question: Do fourth graders tend to be taller than third graders?
This is an observational study. The researcher wants to use grade level to explain differences in height. What is the explanatory variable and the response variable?
The explanatory variable is grade level. The response variable is height.
eliminates possible researcher bias, balances the comparison groups on known as well as on lurking variables.
randomization
What is the difference between Retrospective and Prospective studies?
Retro: case-control study, looks into the past
Prospective: follows subjects iinto the future (cohort)
What type of study is this:
A study randomly assigned volunteers to one of two groups:
Experiment
A team of veterinarians wants to compare the effectiveness of two fertility treatments for pandas in captivity. The two treatments are in-vitro fertilization and male fertility medications. What is the response variable and the explanatory variable?
The explanatory variable: type of fertility treatment. The response variable is a measure of fertility rate.
If someone was given a sugar pill for a treatment, what is that sugar pill called?
Placebo
A university administrator wants to conduct a
survey to examine textbook costs. The university
has eight colleges (business, liberal arts,
engineering, etc.) so the administrator randomly
samples 100 students from each college. This is
an example of what type of sampling method?
Stratified
Selects a sample of people from a population and collects data from them is what?
Sample Survey
A person looks at an unfamiliar crowd of
people and visually selects a sample of 30
individuals for a survey. This is an example of what type of sample?
Bias!
When neither the subject nor those having contact with the subject know the treatment assignment
double blind
Is there a link between prostate cancer and
heating meals in plastic containers in the microwave?
Suppose 300 people with prostate cancer and 300
people of a similar age but without prostate cancer
were asked if they heated food in the microwave in a
plastic container. What type of observational study is
this?
Case-Control Study
What does a census attempt to do?
Attempts to count the number of people in the
population and to measure certain characteristics about them.
What are the three types of bias in sample surveys?
Sampling, nonresponsive, and response
What are the key parts of a good experiment?
A good experiment has a control comparison group,
randomization in assigning experimental units to treatments, and blinding.
What is the difference between Cluster sample and Stratified sample?
Cluster: Divide the population into a large number of
clusters, such as city blocks.
Select a simple random sample of the clusters.
Use the subjects in those clusters as the sample.
Stratified: Divide the population into separate groups, called strata, based on some attribute or characteristic
about the subjects.
Select a simple random sample from each stratum.