Simple Experiments (Week 10)

Question 1

What does a study need in order to be called an experiment?

Answer 1

At least one manipulated variable - controlled by the experimenter
A measured variable - measured by the experimenter

Question 2

What are control variables?

Answer 2

Variables the researchers hold constant

ex: in dominance study all people saw the same character with the same color shirt

Question 3

Why are experiments so useful? what can they establish?

Answer 3

Establish cause and effect because of temporal precedence and internal validity (controlled environment rules out alternative explanations)

Question 4

Different levels of the same IV are called?

Answer 4

Conditions

ex: one group has candy, the other does not

Question 5

What is a placebo control?

Answer 5

A placebo is an inert treatment that is closer to the treatment condition compared to nothing

Question 6

What is a potential, undesirable effect of confounds?

What are selection effects?

Answer 6

Systematic variability - not random, systematic differences between the control and the experimental group

Participants in one condition are systematically different from participants in other conditions

Question 7

What are matched groups? How would a researcher make this division?

Answer 7

Matching takes random assignment one step further and ensures that groups are the same on a key variable
ex: Grp 1 = 1 highest IQ, 1 med IQ, 1 low IQ
Grp 2 = 1 highest IQ, 1 med IQ, 1 low IQ

Question 8

What are the two types of experimental designs and what are their sub-designs?

Answer 8

Between subjects - pretest/post test + post test only

Within subjects - concurrent measures + repeated measures

Question 9

What is a between subjects design?

Provide a brief description and example

Answer 9

Participants are placed into different levels of the IV

1. Post test-only - measure DV once
   ex: does being in nature make you happy - walk in city or forest - take test
2. Pretest + Post test - tested on DV before and after
   ex: “ but take test before and after walk

Question 10

What is a within groups design?

Provide a brief description and example

Answer 10

Participants are exposed to all levels of an independent variable

1. Concurrent measures - exposed to all levels of the experiment at roughly the same time
   ex: babies watch 2 puppets interact, measure which one they look at most
2. Repeated measures - measured on a dependent variable more than once (after each level)
   ex: all participants go for a nature walk - tested - all participants go for a city walk - tested

Question 11

What are the advantages of within group studies?

Hint: there are 3

Answer 11

1. Ensures participants receiving different levels of IV are the same
2. Each person can be treated as their own control
3. More statistical power - more data per level of IV

Question 12

What is the relevance of order effects? name the two listed in class

Answer 12

The order in which participants are exposed can effect their responses

1. Carryover effect - the effects of being one condition first influence the second experience
2. Practice/fatigue effect - people are tired after being in one condition which effects their perception of the second

Question 13

What is a method of overcoming order effects?

Answer 13

Counterbalancing - participants receive the levels of the IV in different orders

Question 14

What are some disadvantages of within groups studies?

Hint: there are 3

Answer 14

1. Order effects
2. Some res questions are impractical - ex: if researching methods for riding a bike, can’t compare the same kids
3. Demand characteristics - greater chance participants will realize the purpose of the study and change behaviour

Question 15

How is statistical significance determined in a experiment? What is this test called?

Answer 15

Compare the means (averages) and the error (variability) around the means
T-test