One goal of stratified sampling plans is to decrease the amount of variability in each
stratum. This can be accomplished by
a. making the strata internally heterogeneous.
b. increasing the amount of sampling error.
c. decreasing the magnitude of the overall sample mean.
d. making the strata internally homogeneous.
e. using a 99% confidence level instead of a 95% confidence level.
Which of the following research scenarios are examples of the observation method?
a. A car dealer checking which radio stations cars are tuned to when they’re brought in
for service, to know which stations to advertise on.
b. Recording license plate information in a shopping mall parking lot to learn where
shoppers are coming from.
c. The use of different colored promotional flyers mailed to different zip codes to
identify which trading area a retailer is serving.
d. Studying scuff marks on tiles at a museum as a means of measuring the popularity of
a display.
e. All of the above are examples of observational research methods.