Randomized Block Design

In order to perform an experiment using 60 members of a gym, I first divide the list of members into men and women because I feel that the results will be different based on gender. I then randomly choose 30 men and 30 women. I assign half of the men to the treatment group and half to the control group. I repeat this procedure with the women. This is an example of a:

• randomized comparative design

• blocking design

• matched pairs design

• double blind simple random sample

In the previous problem, supposed that the researchers suspected that women over the age of 55 may respond differently to the treatment. Given that a random sample of 40,000 women over the age of 45 has already been chosen, the study would have been improved by:

• a stratified sample, with strata determined by age.

• a stratified sample, with strata determined by gender.

• a block design, with blocks determined by age.

• a block design, with blocks determined by gender.

• a double-blind completely randomized design.

To investigate the effectiveness of an herbal medication for pain relief, a researcher randomly selected 80 patients who were undergoing physical therapy while recovering from an injury. Of the patients, 40 had knee injuries, 16 had arm injuries, and 24 had foot injuries. The researcher will use two treatments for the investigation: the herbal medication and a standard medication. After the patients are on the medication for two weeks, the amount of pain reduction will be measured for each patient. Which of the following best describes why a randomized block design is appropriate for the investigation?

• The 80 patients were selected at random from all patients undergoing physical therapy while recovering from an injury.

• The sample size was greater than 30.

• Each patient will be randomly assigned to either the herbal medication or the standard medication.

• Blocking on injury type will help to separate natural variability from differences due to injury type.

• Each patient assigned to the herbal medication will be paired with a patient assigned to the standard medication.

Assigning treatment groups by dividing participants into blocks of subjects with similar characteristics and then within each block you randomly assign subjects to treatment groups

• Randomized Block Design

• Matched Pairs Design

• Random Selection

In ______ units are sorted into subgroups or blocks, and then treatments are randomly assigned within the blocks.

• completely randomized design

• randomized block design

• matched pairs design

• Stratified Random Sampling

What is a randomized block design?

• A type of clinical trial in which neither the participants nor the researcher knows which treatment or intervention participants are receiving until the clinical trial is over.

• Experiment where participants who share certain characteristics are grouped together to form blocks, and then the treatment gets randomly assigned within each block.

• A type of probability sampling method in which sample members from a larger population are selected according to a random starting point but with a fixed, periodic interval.

• Experimental design where participants are matched in pairs based on shared characteristics before they are assigned to groups.

A case of randomized block design where an experiment has two treatment conditions. The subjects are grouped together into pairs based on an equivalent variable. In each pair, one of the subjects is randomly assigned to one treatment and automatically the other subject is assigned to the other.

• 1. Placebo

• 1. Voluntary Response Bias

• 1. Cluster Random Sample

• 1. Matched Pairs

An experiment will be conducted to determine whether children learn their multiplication facts better by practicing with flash cards or by practicing on a computer. Children who volunteer for the experiment will be randomly assigned to one of the two treatments. Because the children’s gender may affect the outcome, there will be blocking by gender. After practice, the children will be given a test on their multiplication facts. Why will it be impossible to conduct a double-blind experiment?

• The experimenter will know whether the child is a boy or a girl and whether he or she used flash cards or the computer.

• The child will know whether he or she is a boy or a girl.

• The child will know whether he or she used flash cards or the computer.

• The person who grades the tests will know whether the child was a boy or a girl.

• The person who grades the tests will know whether the child used flash cards or the computer.

The two graduates with the greatest GPA from each of 14 randomly selected law schools were recruited to investigate a new method of preparation for a law exam. For each school, one student was randomly assigned to prepare using the standard method and the other student was assigned to prepare using the new method. At the end of the preparation, all 28 students were given the same exam, and their scores were recorded. Which of the following best describes why a matched-pairs design is an appropriate design for the investigation?

• Each graduate was randomly assigned to one method.

• The law schools were randomly selected.

• Each method served as a block.

• The sample size was less than 30.

• Each law school served as a block, and the graduates were paired within each law school and randomly assigned to one of the two methods.

When there are a large number of experimental comparison groups, the__________________ is used to bring homogeneity among selected different groups

• Randomized block design

• Pre-Test and Post test Only

• Post-Test Only

• Cross over Design