SAMPLING DESIGNS
These come from measurements made on SAMPLE data.
Statistics
(What are measurements made on population data called?)
This type of sampling design selects individuals that are easiest to reach.
Convenience Sampling
(Should we use this type of sample? Why/Why not?)
This type of experimental design randomly assigns subjects into treatment groups and measures an outcome.
Completely Randomized
***In order to determine the effects of a music and time of day on stress levels, 100 randomly selected subjects are assigned to one of two music groups (classical or rap) and one of three time levels (morning, afternoon, evening). The subject's stress level is measured at the beginning of the study and after 3 months. How many treatments are there in this experiment?***
(2)(3) = 6
***A study found that the average income for all United States citizens was $55,000. The value $55,000 is a ...***
Parameter
A business magazine mailed a questionnaire to the HR directors of all the Fortune 500 companies, and received responses from 23% of them. Those responding reported that they did not find that such surveys intruded significantly on their workday. The most significant source of bias here is ...
Nonresponse Bias
***In order to determine the effects of a healthy diet and exercise on cholesterol levels, 100 randomly selected subjects are assigned to one of three diets (no restriction, 1 vegetable serving, 5 vegetable servings) and one of three exercise groups (no exercise, 30 minutes/day, 60 minutes/day). The subjects' cholesterol is measured at the beginning of the study and after 3 months. How many treatments are there in this experiment?***
(3)(3) = 9
***In a random sample of 50 college students it was determined that the average number of hours spent studying per day was 2.15. The value 2.15 is a ...***
Statistic
Separate the students by class (freshman, sophomore, junior, senior). Pick a simple random sample of size 25 from each of the four groups, and then combine these students into one sample of size 100. What kind of sampling strategy is being used?
Stratified Sampling
Suppose you are conducting a survey regarding illicit drug use among sophomore in the Baltimore School District. You obtain a random sample of 12 schools with the district and have teachers verbally administer the surveys to all sophomores. The most significant source of bias here is ...
Response Bias
***In one study on the effect eating red meat products has on weight level, an SRS of 500 subjects who admitted to eating meat at least once a day had their weights compared with those of an SRS of 500 people who claimed to be vegetarians. In a second study, an SRS of 500 subjects were served at least one meat meal per day for 6 months, while an independent SRS of 500 others were chosen to receive a strictly vegetarian diet for 6 months, with weights compared after 6 months. Describe these studies.***
The first study is an observational study while the second is a controlled experiment.
***A large retail company randomly selects ten of its stores from a list of all the company's U.S. stores. All employees at these ten stores are asked to fill out an employee satisfaction survey. This is an example of ...***
Cluster Sampling
Separate the students by home-room assigned (each home-room has 25 students). Pick a random sample of four home-rooms. If a home-room is selected, all students in that home-room are included in the sample. What kind of sampling strategy is used?
Cluster Sampling
***A news show host asked the viewers to call in to give their opinions about the President's administration. What type of sampling design is this?***
Voluntary Response Sampling
(Why is this included in the bias category?)
You divide 100 plants into two groups (shade and sun). Within each group, you randomly assign plants to one of three types of music (classical, rock, or reggae). The selected type of music is played to each plant for 30 minutes a day over a period of 6 weeks. What type of experimental design is being employed?
Block Design
*** T/F: A lurking variable affects both the explanatory and response variable of a study.***
TRUE
(What variable only affects the response variable?)
***Suppose that a researcher in CA wants to take a statewide survey regarding state budgetary issues. The researcher creates a sample by randomly selecting 50 people from each county in the state. What term best describes the type of sample that is being created?***
Stratified Sampling
***In a survey to estimate the level of overall public support in the entire United States for the proposal of equal pay and benefits for adjunct lecturers, a random sample of adults in CA is selected. The most significant bias introduced here is ...***
Undercoverage
***An experiment is being performed to test the effects of a new drug on reducing the level of someone's depression. 500 subjects diagnosed with depression participated in the experiment. The subjects' level of depression was measured prior to the experiment and measured again after taking the drug. What type of experimental design is being used for this experiment?***
Matched Pair
***A researcher company decides to test the effect of a drug meant to reduce the intensity of migraine headaches. Two groups are tested. One group is given the drug and the other group is given a placebo. Length of relief from the headache is recorded. The test is done as a double-blind study. What is meant by double-blind?***
Neither the patient nor the doctor administering the pill knows whether the pill is the actual drug or the placebo.