Section 1.3 Collected Work
Name: _________________________
Instructions: Show your work neatly and systematically for full credit.
1. Identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.
a. A farmer divides his orchard into 50 subsections, randomly selects 4, and samples all the trees within the 4
subsections to approximate the yield of his orchard.
b. A survey regarding download time on a certain website is administered on the Internet by a market research
firm to anyone who would like to take it.
c. A college official divides the student population into five classes: freshman, sophomore, junior, senior, and
graduate student. The official takes a simple random sample from each class and asks the members’
opinions regarding student services.
d. To estimate the percentage of defects in a recent manufacturing batch, a quality-control manager at Intel
selects every 8th chip that comes off the assembly line starting with the 3rd until she obtains a sample of 140
chips.
2. Determine whether the study is an experiment or an observational study. For observation study, determine
whether cross-sectional, retrospective, or prospective is used.
a. Rats with cancer are divided into two groups. One group receives 5 mg f mediation that is thought to fight
cancer, and the other receives 10 mg. After 2 years, the spread of the cancer is measured.
b. Conservation agents netted 250 large-mouth bass in a lake and determine who many were carrying
parasites.
c. Two hundred people are asked to perform a taste test in which they drink from two randomly placed,
unmarked cups and asked which drink they prefer.
d. Samples of subjects with and without heart disease were selected, and then researchers looked back in time
to determine whether they took aspirin on a regular basis.
3. Identify which of these designs is most appropriate for the given experiment: completely randomized design,
randomized block design, or matched pairs design.
Currently, there is no approved vaccine for the prevention of infection by West Nile virus. A clinical trial of a
possible vaccine is being planned to include subjects treated with the vaccine while other subjects are given
a placebo.