STATS UNIT 2
use scenario 4-4: another correct choice of labels for the 816 students is
400, 769, 335
use eight student scenario: choose a simple random sample
Alvarez, Barlow, Salter, and Verducci
use list of names scenario: the simple random sample is
Bechhofer, Taylor, Weiss
use scenario 4-4: another correct choice of labels for the 816
Both (B) and (C) are correct
cholesterol scenario: which of the following best describes the inferences the researcher can make based in his results
He can make inferences about the populations from which the samples were taken, but not cause and effect
use list of names scenario: which of these statements about the tale of random digits is true
None of these are true
a poll conducted by the student newspaper asked, "who do you believe will win the Ohio State..."
The results of the survey are unreliable because response to the survey was voluntary
Use Lafayette scenario: the newspaper asks you to comment on their survey
This is a convenience sample. It will almost certainly overestimate the level of support among all Lafayette residents
In order to assess the opinion of students at the University of Minnesota, snow removal
a convenience sample
a simple random sample is
a sample that gives every possible sample of the same size the same chance to be selected
a lurking variable is
a variable that is not among the variables studied but that affects the response variable
when controlled experiments are impractical or unethical
all of the above
Lafayette residents, first 20 people
all residents of Lafayette
A news release for a diet products company reports:
biased, overstating the effectiveness of the diet
a study sponsored by American Express Co
biased, overstating the extent to which the old stereotypes
which of the following statements about randomized block design
block a is chosen randomly from among the available experimental units
caffeine performance scenario: randomly allocated
block design
which of the following is not a major principle of good design for all experimets
blocking
To determine the proportion of each color of Peanut Butter M&M, you buy 10 1.69 ounce packages and count
cluster sampling
a marine biologist wants to estimate the mean size of the barnacle in Semibalanus
cluster sampling
if changes in a response variable are due to the effects of the explanatory variable as well as the effects of
confounding
use caffeine performance example: unfortunately, any difference could be due to the two sessions having different teachers
confounding
the principle reason for the use of random assignment in designing experiments is that it
creates apporx. equal groups for comparison
the principle reason for the use of controls in designing experiments is that it
distinguishes a treatment effect from the effects of confounding variables
cholesterol scenario: this is a(n)
double blind experiment
double blind experiment was conducted to evaulate effectiveness of polio vaccine
eliminate possible source of bias
caffeine performance scenario: the response variable is
exam performance
the most important advantage of experiments over observational studies is that
experiments can give better evidence of causation
heart rate and steps
factors
use list of names scenario: which of the following statements is true
if we use another list of random digits to select the sample, the result obtained with the list actually used would be just as likely to be selected as any other set of three names
an example of a non-sampling error that can reduce the accuracy
many members of the sample cannot by contacted
spaghetti sauce
matched pairs
dogs disks (black and red)
matched pairs design
kindergarten class
may be confounding variables in this study
an opinion research firm wants to find the country's reaction by a famous politician
multistage sampling
simple random sampling
none of the above
frequently, telephone poll-takers call near dinner time - between 6 pm and 7 pm -
nonresponse
the essential difference between an experiment and an observational study is
observational studies are always biased
caffeine performance example: coffee taste bad
placebo effect
blocking is used sometimes to
reduce variability from arising in random assignment
principle reason for replication
reduces sampling variability
The Bradley effect is a theory proposed to explain observed discrepancies between voter opinion polls and election outcomes in some elections
response bias
in an experiment, an observed effect so large that it would rarely occur by chance is called
statistically significant
A public opinion poll in Ohio wants to determine whether or not registered voters in the state approve of a measure
stratified random sample
we divide the class into two groups: first-year students and others. We then take random samples from each group
stratified random sampling
you plan to give a math achievement test to samples of 15 year olds from both the US and Korea in order to compare
stratified random sampling
Medical researchers are excited about a new cancer treatment that destroys tumors by cutting off their blood supply
suffers from realism
medication scenario: the experimental units are
the 100 volunteers
Use Lafayette example: The sample for the survey is
the 20 people who gave the sportswriter their opinion
in comparative trials in medicine the placebo effect can be avoided
the double blind technique
a stratified random sample is appropriate when
the population can be easily subdivided into groups according to some categorical variable, and the variable you are
a 1992 roper poll found that 22% of Americans say that the holocaust
the question is worded in a confusing manner
A marketing research firm wishes to determine if the adult men in Laramie
the same as for any other set of 100 residential addresses
medication scenario: which describes inferences that can be made
they can make inferences about cause and effect, but not about population from which samples were taken
Just before the presidential elction of 1936 the magazine Literary digest
undercoverage
a local tax reform group polls the residents of the school district
underestimate support for arts programs because of nonsampling error
a television station is interested in predicting whether voters in its viewing area in favor
voluntary response sample
twelve people who suffer from chronic fatigue
we believe men and women will react differently
A market research company wishes to find out whether the population of students at a university prefers brand A or brand B of coffee. Response variable?
which brand they prefer
100 volunteers suffer from depression
which treatment volunteers recieve