Definitions Flashcards
Ratio scales
have equal intervals between adjacent scores on the scale and an absolute 0.
Interval scales
have equal intervals between adjacent scores but do not have an adjacent 0.
Ordinal scales
have some sort of order to the categories but the intervals between adjacent points on the scale are not necessarily equal
Extraneous variables
might have an impact on the other variables that we are interested in but may have failed to take these into account when designing the study
Confounding variables
are a specific type of extraneous variable that is related to both of the main variables we are interested in.
correlational designs
those that investigate relationships between variables
experimental designs
where the experiment manipulates the IV to see what effect this has upon the DV
Quasi-experimental designs
involve seeing if there are differences on the DV between conditions of the IV. Unlike experimental designs, there is no random allocation of participants to the various conditions of the IV.
within participants deisgns
have the same participants in every condition of the IV. Each participant performs under all conditions in the study.
order effects
are a consequence of a within participants design whereby completing the conditions in a particular order leads to differences in the DV that are not a result of the manipulation of the IV.
Counterbalancing
Where you systematically vary the order in which participants take part in the various conditions of the IV.
Between participants designs
have different groups of participants in each condition of the IV. Thus, the group of participants in one condition of the IV is different from the participants in another condition of the IV
Between participants advantages
- relative absence of practice and fatigue effects
- participants less likely to work out purpose of study
Between participants disadvantages
- need more participants
- not as much control of confounding variables between conditions
Within participants advantages
- need fewer participants
- greater control of confounding variables between conditions
Within participants disadvantages
- increased likelihood of practice or fatigue effects
- participants more likely to guess purpose of the study
Population
consists of all possible people or items who/which have a particular characteristic
Sample
refers to a selection of individual people or items from a population
parameters
descriptions of populations whereas statistics are descriptions of samples
Measures of central tenendcy
give us an indication of the typical score in our sample. it is effectively an estimate of the middle point of our distribution of scores