Experimental Design and Block Design Test Review

The thing to which the treatments are assigned

• experimental unit

• level

• response variable

• factor

Fill in the blanks:

___ eliminates lurking variables

___ isolates lurking variables

___ distributes lurking variables

• Control, Blocking, Randomization

• Blocking, Control, Randomization

• Randomization, Replication, Control

• Control, Randomization, Blocking

Thirty-six students at a local middle school were randomly selected to participate in a taste test to select a new menu item for a cafeteria. Each student was given a choice between the macaroni and cheese and the Cajun potato barrels. From the sample, 20 students selected macaroni and cheese and 16 students chose the Cajun potato barrels. Each student was asked to rate the item they chose on a scale from 1 (extremely dislike) to 9 (extremely like). Which of the following prevents this study from being a well-designed experiment?

• There was no replication because students did not eat both menu items.

• The treatments (new menu item) were not randomly assigned to the students.

• An item that is currently on the menu should have been used as a control.

• Students should not have been randomly selected.

• There were no problems, and the study was a well-designed experiment.

A researcher randomly selected 30 people to participate in a study to investigate which of two materials, A or B, used in the heels of sneakers will last longer. The researcher is considering two design types for the study. Which of the following best describes each design?

• Design 1 is a completely randomized design, and design 2 is a matched pairs design.

• Design 1 is a matched pairs design, and design 2 is a completely randomized design.

• Design 1 is a matched pairs design, and design 2 is a matched pairs design.

• Design 1 is a completely randomized design, and design 2 is a completely randomized design.

• Design 1 is a completely randomized design, and design 2 is a randomized block with materials as blocks.

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

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

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

• blocking

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.

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.

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.