Chapter 1.3- Collecting Sample Data

Identify which of sampling is used: random, systematic, convenience, stratified, or cluster: An internet site asks its members to call in their opinion regarding their web searching habits

Convenience

Determine whether the study is an experiment or an observational study, and then identify the major problem with the study: A study involved 22,071 male physicians. Based on random selections, 11,037 of them were treated with aspirin and the other 11,034 were given placebo. The study was stopped early because it became clear that aspirin reduced the risk of mycardinal infarcations by a substantial amount

-This is an experiment because the researchers apply a treatment to the individuals -The major problem with the study is the results apply only to male physicians

Determine whether the study is an experiment or an observational study, and then identify the major problem with the study: A medical researcher tested for a difference in systolic blood pressure levels between male and female students who are 12 years of age. She randomly selected 4 males and 4 females for her study

-This is an observational study because the researcher does not modify the individuals -The major problem with the study is the sample is too small

Identify the type of observational study described below: A research company uses a device to record the viewing habits of about 15,000 households, and the data collected over the next 8 years will be used to determine whether the proportion of households turned to a particular educational program decreases

A prospective study

Identify which type of sampling is used: random, systematic, convenience, stratified, or cluster: To determine customer opinion of their inflight service, Continental Airlines randomly selects 70 flights during a certain week and surveys all passengers on the flights

Cluster

Explain the difference between a single-blind and a double-blind experiment

In a single-blind experiment, the subject does not know which treatment is received. In a double-blind experiment, neither the subject nor the researchers in contact with the subject knows which received treatment

Identify the type of sampling method used in the situation described below: A woman is selected by a marketing company to participate in paid focus group. The company says that the woman was selected because she was randomly chosen from all adults

Random Sampling

Determine whether the description corresponds to an observational study or experiment: Research is conducted to determine if there is a relation between height and childhood exposure to measles

Observational Study

Identify the type of sampling method used in the situation described below: In a poll conducted by a certain research center, 932 adults were called after their telephone numbers were randomly generated by a computer, and 13% were able to correctly identify the secretary of state

Random Sampling

Identify which type of sampling is used: random, systematic, convenience, stratified or cluster: To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Toshiba selects every 12th laptop that comes off the assembly line starting with the 4th until the obtains a sample of 30 laptops.

Systematic

Identify the type of sampling method used in the situation described below: A researcher selects every 476th social security number and surveys the corresponding person

Systematic Sampling

Determine whether the given description corresponds to an observational study or experiment: In a study of 367 students with a particular disease, the subjects were monitored with an EEG while asleep

The given description corresponds to an observational study

In a study designed to test the effectiveness of a medication as a treatment for lower back pain, 1643 patients were randomly assigned to one of the three groups: (1) 547 subjects in the placebo group were given pills containing no medication, (2) 550 subjects were in a group given pills with the medication taken at regular intervals, (3) 546 subjects were in a group given pills with the medication to be taken when needed for pain relief. In what specific way was replication applied in this study?

The group sample sizes are all large so the researchers could see the effects of the treatment

Identify which of these designs is the 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 a certain virus. A clinical trail of a possible vaccine is being planned to include subjects treated with the vaccine with the other subjects are given a placebo

The most appropriate is completely randomized design

Identify which of these designs is the most appropriate for the given experiment: completely randomized design, randomized block design, or matched pairs design A drug is designed to treat insomnia. In a clinical trail of the drug, amounts of sleep each night are measured before and after subjects have been treated with the drug

The most appropriate is matched pairs design