Psych Unit 1 Key terms FIA1 and IA1

psychology yr 11 and 12 students

IV

the variable that is manipulated by the experimenter who then measures resulting changes in the DV

Null hypothesis

no significant difference between groups; any difference observed is caused by error

DV

property that is measured in psychological research, to look for effects of the IV

alternative hypothesis

hypothesis that states there will be a relationship between the IV and DV

population

group of people about which we wish to draw conclusions

sample

the members of the pop who have been chosen to take part int eh research

convenience sampling

using whoever is available at the time of research

random sampling

a sampling procedure in which every member of the pop has an equal chance of being selected

independent groups design

allocates participants to E or C group at random

Sd

how far on average the scores differ from the mean

quantitative data

measurements (numerical) about variables being studied

qualitative

descriptions of the characteristics of what is being studied

nominal data

qualitative rather than quantitative value, no ranking or ordering of values implied

interval data

data measured on a scale where each step is the same value, but 0 does not mean that the property does not exist

ratio data

measurements that represent quantities in terms of equal intervals and an absolute 0 point of origin

reliability

extent to which a measure could be expected to produce the same results under the same conditions with the same subject(s) on other occasions

validity

extent to which an instrument measures what it is supposed to measure

mean

average of all scores by adding up all the scores and dividing that total by the no. of scores

median

middle no. of the data set in numerical order

mode

most common/occurring score in data set

E group

group that is exposed to the IV, results compared with C group so the effects of the IV can be determined

C group

group of research participants NOT exposed to the IV variations, the results are compared with the experimental group so that the effects of the IV can be determined

ordinal data

definite sequence but the gap between one level and next not consistent

repeated measures design

each participant is part of E and C group. subject selection procedure

matched participants design

attempts to eliminate confounding variables by ‘matching’ on key characteristics, each individual in the E group with an individual in the C group

t-test

comparison of means in data that reveals how significant the differences are

Mann-Whitney U test

used for ordinal data to test whether 2 means are = or not. test of null hypothesis. used to compare differences between groups when the DV is ordinal or continuous

Wilcoxen signed-rank test

compares 2 sets of scores from the same data set of participants when the data is not normally distributed. alternative to t-test.