research methods Flashcards
null hypothesis + example
no difference
there is no difference between eating eggs and an increase in bone strength
directional hypothesis + example
this is the difference
eating eggs will increase bone strength
non directional
is a difference
is a difference between people eating eggs and their bone strength
sign test
non-parametric statistical test of difference that allows a researcher to determine the significance of their investigation.
when to use sign test
data is nominal and a repeat measures has been used.
nominal data
names/categories e.g. red, green, blue
ordinal data
ranked e.g. exam results
interval data
ordered data that occurs at regular intervals e.g. sec, min, cm, mm, kg
TABLE
unrelated | related | correlational/association
nominal
ordinal
intervalTABLE ANSWERS
unrelated | related | correlational/association
nominal | ch-sq. | sign Test | chi -squared
ordinal | Mann-whit| Wilcoxon | spearman’s rho
interval. | unrelat t-test | relat t-test | Pearsons R
type 1 error
when null hypothesis is rejected and alternative hypothesis is accepted however should have been the other way round as the null hypothesis is correct
(telling a man he is pregnant)
type 2 error
null hypothesis is accepted but it should have been the alternative hypothesis because this is in fact true
(telling a pregnant woman she isn’t pregnant)
sign test requires…
observed value to be equal to or less than the critical value in order to be accepted as significant allowing the null hypothesis to be rejected
type 1 error is likely
if the significance level is too high e.g. 0.1 or 10% rather than 5%
type 2 error is more likely
if the significance level is too low e.g. 0.01 or 1%
why is this?
potential significant values may be missed
