Experimental Design (Sept 11/13)

Question 1

What is the difference between experiment design and non experimental design

Answer 1

Experimental design allows us the establish a causal relationship between 2 variables
Non experimental doesn’t

Question 2

What is the purpose of ED and NED

Answer 2

ED - to establish a cause and effect relationship
NED- to observe and describe phenomena

Question 3

How much control do we have over variables in ED vs NED

Answer 3

ED- high control over independent through manipulation
NED - no manipulation of variables, variables are observed as they naturally occur.

Question 4

How does random assignment work in ED vs NED

Answer 4

ED - participants are randomly assigned to groups (control and experimental)
NED - no random assignment because groups are pre-existing or naturally occurring which would make it impossible or unethical.

Question 5

When should you chose experimental design

Answer 5

• have a hypothesis about causal relationships between 2 variables
• you are able to manipulate the indepent variable
• you can randomly assign participants to different groups in the indepent variable

Question 6

What is the difference between random assignment and random sampling

Answer 6

Random sampling is where we randomly pick participants from the population whereas random assignment is randomly choosing which participants are going to be apart of which group in the experiment.

Question 7

When is a non-experimental design good?

Answer 7

• you are interested in a single variable
• you are interested in a non-causal relationship between 2 variables (correlation)
• you have an exploratory research topic

Question 8

NED: what is cross sectional

Answer 8

You compare 2 or more pre-existing groups (you don’t create the groups

Question 9

NED: what is correlational

Answer 9

You see if 2 variables are correlated

Question 10

NED: what is an observational study

Answer 10

You observe the behaviour in a natural or lab setting without manipulation

Question 11

True-experimental design vs Quasi- experimental design

Answer 11

True - random assignment is possible
Quasi- random assignment is unethical or impossible

Question 12

How does intervention and random assignment work in QED vs NED

Answer 12

QED - an intervention is made but no random sampling
NED - no intervention is made, no random sampling or group manipulation

Question 13

How does causality work in QED vs NED

Answer 13

QED - attempts to establish causality but less certainty due to lack of randomization
NED - cannot determine causality only correlation

Question 14

Is there a need for comparison groups in QED vs NED

Answer 14

QED - often include comparison or control groups but not randomly assigned
NED - may not have comparison or control groups

Question 15

Dependent vs independent variables

Answer 15

Depend - the variable you measure
Independent- the variable you manipulate.

Question 16

What are levels in independent variable

Answer 16

Levels are groups within the indepent variable
Ex. Sex - male and female

Question 17

What is an extraneous variable

Answer 17

Variables that are not the indepent variable but may have an effect on the dependent variable
(Example slide 15 experimental design)

Question 18

What are confounding variables

Answer 18

An extraneous variable that potentially ended up affecting the dependent variable (example slide 16)

Question 19

What is a lurking variable

Answer 19

A lurking variable is a variable that affects both independent and dependent variables

Question 20

Pretext- Protest design

Answer 20

DV measured before intervention - intervention is made - DV measured again

If DV isn’t measured pre-intervention it’s not a pretext-protest or true experimental design

Question 21

What is factorial design

Answer 21

When there are more than one indepent variable in a single experiemnt without the need to run separate experiments it is factorial.

Question 22

What is a single-factor design:

Answer 22

when you have a single factor/independent variable in the experiment.

Question 23

What is a univariate design

Answer 23

When you have a single dependent variable

Question 24

What is a single-factor univariate design?

Answer 24

has one independent variable and one dependent variable

Question 25

Poll:

We have a study with 2x3 factorial design. How many independent variables?

Answer 25

2

Question 26

Poll:

we have a study with a 2x3 factorial desin. What does ‘3’ indicate here?

Answer 26

number of levels in the second independent variable.