1.6 Probability

Question 1

define alternative hypothesis

Answer 1

a testable statement about the relationship (difference, association etc.) between two or more variables

Question 2

define null hypothesis

Answer 2

an assumption that there is no relationship (difference, association etc.) in the population from which a sample is taken with respect to the variables being studied

Question 3

define ‘probability (p)’

Answer 3

A numerical measure of the likelihood or chance that certain events will occur
a statistical test gives the probability that a particular set of data did not occur by chance

Question 4

define type 1 error

Answer 4

occurs when a researcher rejects a null hypothesis that is true

Question 5

define type 2 error

Answer 5

occurs when a researcher accepts a null hypothesis that was not true

Question 6

summarise probability

Answer 6

a numerical measure of the likelihood or chance that certain events will occur
null hypothesis - a statement of no relationship. How probable is the research result if there is actually ‘nothing going on?’
chance is something without any cause. Is a result due to chance or a real effect?
psychologists use the 95% level: p = 0.05 means 5% possibility that a result is due to chance, 95% possibility that it is a real effect (there is something going on)
in research concerning e.g. life and death matters, probability level (p) is 0.01 of 1%
type 1 error - rejecting a null hypothesis that is true
type 2 error - accepting a null hypothesis that is false