RM 4 (inferential stats)

descriptive statistics

analysing data at face value to see any patterns or trends

inferential statistics

to see if any difference or relationship is significant

what is the general level of significance

0.05

how many tests do you need to know

8

three questions to decide which test

independent or related, difference or correlation, level of data

type 1 error

level of significance is too lenient (alternate hypothesis is incorrectly accepted)

type 2 error

level of significance is too strict (null hypothesis is incorrectly accepted)

when is the sign test used

when looking for a difference, data is nominal and the design is related

which tailed test for a directional hypothesis

one-tailed test

when is spearmans rho used

looking for a relationship, data is ordinal, design is related

when is chi squared used

when looking for a difference, data is nominal, design is unrelated

when is wilcoxon test used

looking for a difference, data is ordinal or interval, design is related

when us mann whitney test used

looking for a difference, data is ordinal or interval, design is independent

when are parametric tests used

data is interval, data has a normal distribution, variances of the samples assumed to be the same

when is pearson’s R used

when parametric conditions are met, the design is related, looking for a relationship, data is interval

when is the unrelated t-test used

when parametric conditions are met, design is unrelated, data is interval, looking for a difference

when is the related t-test used

parametric conditions are met, looking for a difference, design is related, interval data

parametric tests

related and unrelated t-tests, pearson’s R

correlation co-efficient

shows the direction and strength of the correlation

how are most extraneous variables controlled

a big enough sample

how are most confounding variables controlled

they may require a change in the design

mnemonic

carrots should come mashed with swede under roast potatoes

what does the mneonic stand for

chi, sign, chi, mann-whitney, wilcoxon, spearman’s rho, unrelated, related, pearsons

left side of table

nominal, ordinal, interval

top of the table

independent, matched pairs, correlation