Exam 13: Quasi-Experiments and Small-N Designs

Dr.Fletcher is interested in whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance.He recruits a group of 55 freshmen (25 males,30 females)who are planning to go through fraternity/sorority recruitment on his campus.After they join,he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale). -In addition to measuring the body concern of the participants who joined a fraternity/sorority both immediately before and immediately after they join,Dr.Fletcher measures them for the three weeks before and the three weeks after.This type of design is known as a/an:

Explain how interrogating the statistical validity of a small-N design is different from interrogating the statistical validity in a large-N design.

According to the textbook,which of the following ethical questions might be posed specifically in reference to a reversal design?

Why do quasi-experiments tend to have very good construct validity for the independent variable?

The fact that the researcher does not have experimental control over the independent variable and does not randomly assign participants to conditions results in a quasi-experimental design with results in which of the following?

A wait-list design is helpful in dealing with which of the following threats to internal validity?

Dr.Anderson is a nutritionist who helps clients lose weight prior to surgery.She is working with W.J. ,a male client who is planning on undergoing a heart transplant.He currently eats more than 3,500 calories a day and has been asked by his doctor to cut the number of calories to about 1,800 (400 for breakfast,600 for lunch,and 800 for dinner).She is curious as to whether a food journal will help W.J.reduce the number of calories he eats.A food journal is used to record everything a person eats.Dr.Anderson decides to phase in the food journal gradually,initially only recording what is eaten at breakfast during the first three days after baseline (days 4-6).During days 7-9,the journal is used at lunch,too,and during days 10-12,it also is used during dinner.Each day,Dr.Anderson's client sends her entries from the food journal and the number of calories he ate at each meal (as calculated by his wife,whose help she enlisted).The data for Dr.Anderson's study are below. -In examining the external validity of her study,Dr.Anderson is probably most concerned about making sure her study generalizes to:

Dr.Fletcher is interested in whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance.He recruits a group of 55 freshmen (25 males,30 females)who are planning to go through fraternity/sorority recruitment on his campus.After they join,he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale). -In addition to measuring the body concern of the participants who joined a fraternity/sorority both immediately before and immediately after they join,Dr.Fletcher measures them for the three weeks before and the three weeks after.This type of design would be able to better address which of the following threats to internal validity?

Dr.Anderson is a nutritionist who helps clients lose weight prior to surgery.She is working with W.J. ,a male client who is planning on undergoing a heart transplant.He currently eats more than 3,500 calories a day and has been asked by his doctor to cut the number of calories to about 1,800 (400 for breakfast,600 for lunch,and 800 for dinner).She is curious as to whether a food journal will help W.J.reduce the number of calories he eats.A food journal is used to record everything a person eats.Dr.Anderson decides to phase in the food journal gradually,initially only recording what is eaten at breakfast during the first three days after baseline (days 4-6).During days 7-9,the journal is used at lunch,too,and during days 10-12,it also is used during dinner.Each day,Dr.Anderson's client sends her entries from the food journal and the number of calories he ate at each meal (as calculated by his wife,whose help she enlisted).The data for Dr.Anderson's study are below. -What type of small-N design has Dr.Anderson used with W.J.?

Dr.Fletcher is interested in whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance.He recruits a group of 55 freshmen (25 males,30 females)who are planning to go through fraternity/sorority recruitment on his campus.After they join,he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale). -Which of the following would Dr.Fletcher need to do to his current study design to make it an interrupted time-series design?

Dr.Fletcher is interested in understanding whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance.He recruits a group of 55 freshmen (25 males,30 females)who are planning to go through fraternity/sorority recruitment on his campus.After they join,he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale,where higher scores indicate higher body concerns). -In addition to measuring the group of participants who joined a fraternity/sorority,Dr.Fletcher decides to give the same measure to another group of 55 participants who decided to not join a fraternity/sorority.Based on the results below,explain whether Dr.Fletcher should be concerned about a history threat to internal validity.

In which of the following ways are correlational designs similar to quasi-experimental designs?

Which of the following is a difference between true experiments and quasi-experiments?

Dr.Anderson is a nutritionist who helps clients lose weight prior to surgery.She is working with W.J. ,a male client who is planning on undergoing a heart transplant.He currently eats more than 3,500 calories a day and has been asked by his doctor to cut the number of calories to about 1,800 (400 for breakfast,600 for lunch,and 800 for dinner).She is curious as to whether a food journal will help W.J.reduce the number of calories he eats.A food journal is used to record everything a person eats.Dr.Anderson decides to phase in the food journal gradually,initially only recording what is eaten at breakfast during the first three days after baseline (days 4-6).During days 7-9,the journal is used at lunch,too,and during days 10-12,it also is used during dinner.Each day,Dr.Anderson's client sends her entries from the food journal and the number of calories he ate at each meal (as calculated by his wife,whose help she enlisted).The data for Dr.Anderson's study are below. -In interrogating the construct validity of Dr.Anderson's study,which of the following might be asked?

Dr.Fletcher is interested in whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance.He recruits a group of 55 freshmen (25 males,30 females)who are planning to go through fraternity/sorority recruitment on his campus.After they join,he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale). -In addition to measuring the group of participants who joined a fraternity/sorority,Dr.Fletcher decides to give the same measure to another group of 55 participants who decided to not join a fraternity/sorority.Doing this would help Dr.Fletcher address all of the following threats to internal validity EXCEPT:

Seeing stability in a stable-baseline design can help rule out which of the following threats to internal validity?

Dr.Fletcher is interested in understanding whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance.He recruits a group of 55 freshmen (25 males,30 females)who are planning to go through fraternity/sorority recruitment on his campus.After they join,he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale,where higher scores indicate higher body concerns). -Explain why Dr.Fletcher is conducting a quasi-experimental design rather than a true experiment.

List the three differences between small-N and large-N designs.

A small-N design that involves providing treatment and then removing treatment is known as a/an:

Dr.Anderson is a nutritionist who helps clients lose weight prior to surgery.She is working with W.J. ,a male client who is planning on undergoing a heart transplant.He currently eats more than 3,500 calories a day and has been asked by his doctor to cut the number of calories to about 1,800 (400 for breakfast,600 for lunch,and 800 for dinner).She is curious as to whether a food journal will help W.J.reduce the number of calories he eats.A food journal is used to record everything a person eats.Dr.Anderson decides to phase in the food journal gradually,initially only recording what is eaten at breakfast during the first three days after baseline (days 4-6).During days 7-9,the journal is used at lunch,too,and during days 10-12,it also is used during dinner.Each day,Dr.Anderson's client sends her entries from the food journal and the number of calories he ate at each meal (as calculated by his wife,whose help she enlisted).The data for Dr.Anderson's study are below. -If Dr.Anderson wanted to keep the same general design,she could use all the following baselines EXCEPT: