Lecture 1

Question 1

3 types of research

Answer 1

1. descriptive research - what is the incidence?
2. relational research - relationship between variables
3. experimental research - does x cause y

Question 2

when does an experiment have high internal validity`?

Answer 2

high internal validity:

> no counfounds

> independent variable must be the cause of the effect on the dependent variable

Question 3

show two group means, connected by line (and not a scatterplot)

> disadvantage?

Answer 3

disadvantage: loss of information on variability within groups

Question 4

what is the problem with inferential statistics?

Answer 4

we can never be sure that the observed effect in our sample also exists in the population

> express uncertainty in probabilities

Question 5

p is dependent on which 3 factors?

what direction?

Answer 5

p depends on:

1. mean effect is greater -> smaller p
2. variance is smaller -> smaller p
3. bigger sample size -> smaller p

Question 6

what does the p value represent in a distribution?

Answer 6

p value: propability of a outcome or a more extreme outcome

Question 7

one sided vs two sided testing

when?

Answer 7

two sided testing:

> your H1 is not directional, you need to test in both directions

one sided testing:

> making assumptions prior to data collection

> H1 is directional