inferential statistics Flashcards
what is a directional hypothesis
a testable statement that states the relationship and direction between two variables
what is a non directional hypothesis
a testable statement that states the relationship between two variables
what is the null hypothesis also known as
H0
what is the null hypothesis
no difference between conditions and variable
why do we run statistical tests in psychology research
determines which hypothesis is true and whether it should be accepted or rejected
what does probability mean
likelihood measurement of a particular event occuring
what is the significance level
point at which researcher can claim to discover a strong correlation or difference
what signifance level is used in all stats tests
5%
why can psychologists never be certain about a certain result
not tested all members of the population
why is the significance level 1% for certain studies
used when human life is at risk
what is the rule of r
statistical tests containing letter r have calculated value equal to or more than critical value
what is the use of a critical value
comparing with the calculated value to conclude whether to reject or accept null hypothesis
what are the three criteria for the table of critical values
- is the critical value one or two tailed
- how many participants in the study
- level of significance in study
what is a type 1 error
null hypothesis is rejected and alternative hypothesis is accepted
- believing something’s happening but nothing took place
- should be opposite in reality
-‘false positive’
what is a type 2 error
null hypothesis is accepted and alternative hypothesis is rejected
-believing nothing has happened but something did take place
-in reality, true alternative hypothesis
- likely during very low significance level
what are the three steps to knowing what statistical test to use
- is researcher looking for a difference or correlation
- if it is a difference, what is the experimental design being used
- what is the level of measurement
what is a related design
able to compare data as it shares some characteristics
what are the three types of quantitative data
nominal, ordinal and interval data
what is nominal data
data represented in categories
- discrete: only appears in one category
e.g. how old are you? ticking relevant box given. only fit into one category
what is ordinal data
data that is viewed as subjective
- unequal intervals
e.g. on a scale of 1-10, how much do you like exercising
what is a limitation of ordinal data
lacks precision as it is based on opinions
what is interval data
based on numerical scales
-most precise data
e.g. time taken to solve a puzzle
draw out the table for statistical tests
how do you work out degrees of freedom for related t test
(N-1)
what are the three reasons for using the sign test
- test of difference
- nominal data
- related design (repeated measures or matched pairs)
how do you work out degrees of freedom for unrelated t test
(Na) + (Nb) -2
how do you work out degrees of freedom for chi squared
(no. of rows-1) x (no. of columns-1)
what are the degrees of freedom
number of values in final calculation of statistics that are free to vary
how do you work out degrees of freedom for Pearson’s r
(N-2)
