Chapter 9 - Experiments

Question 1

What is some language used in experiments?

Answer 1

1. treatment
2. Dependent variables
   - outcomes in experimental research
3. pretest
   - measurement of dependent variable prior to treatment
4. post test
   - measurement of the dependent variable after treatment
5. experimental group
   - receives treatment
6. control group
   - does not receive treatment
7. random assignment

Question 2

What are some types of design?

Answer 2

1. classical experimental design
   - all designs are variations of this
   - contain all language
2. pre-experimental design
   - lack random assignment
3. one group protest post test design
   - no control group
   - no random assignment
4. static group comparison
   - lacks random assignment and pretest
5. two group post test only
   - similar to static group except groups are randomly designed
6. interrupted time series
   - dependent variable is measured multiple times across a period of time
7. equivalent time series
   - over time; repeated pretest, treatment and post test
8. Latin square designs
   - interested in the sequence or order of treatment has an effect

Question 3

What is a design notation?

Answer 3

name of a symbol system used to discuss the parts of an experiment and make diagrams of them

Question 4

What are some threats to internal validity?

Answer 4

1. selection bias
   - threat that research participants will not form equivalent groups
2. History effects
   - threat that an event unrelated to the treatment will occur during the experiment and influence the dependent variable
3. maturation
   - threat that some biological, psychological or emotional process within the subjects and separate them from treatment will change over time
4. testing effect
   - test itself affects dependent variable
5. Morality
   - attrition when some participants don’t participate throughout the experiment
6. statistical regression
   - extreme values pull the average of other results up or down
   - random errors move group results towards the average
7. Diffusion of treatment
   - participants communicate with one another
8. Experimenter expectancy
   - through actions experimenters convey what they expect of participants

Question 5

What is a double blind experiment?

Answer 5

• people who have direct contact with subjects do not know the details of the hypothesis or treatment

Question 6

What is a placebo?

Answer 6

false treatment or had no effect in experiment

Question 7

What is external validity?

Answer 7

• ability to generalize results of an experiment beyond the study itself

Question 8

What is reactivity?

Answer 8

• participants that react differently in a study based on the fact that they are under study

Question 9

What are field experiments?

Answer 9

• conducted in real life settings
• participants are unaware of involvement

Question 10

What is a natural experiment?

Answer 10

• quasi-experimental designs when researchers can use a natural change in society and measure an outcome before and after the change

Question 11

Piff reading