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Investigation Design Aims and Hypotheses
Aim = intended purpose of an investigation
Hypothesis = a specific statement of what the psychologist wants to test e.g. alcohol makes people
Null Hypothesis = the IV will not have any effect on the DV e.g. alcohol will not have an effect on
Experimental Hypothesis = statement that predicts that a difference or an expected relationship
between two variables will e revealed by the research findings. E.g. the type of alcohol drink
(spirits or lager) will have different effects on people's aggressive behaviour. (can only be used
for experiments to establish a cause and effect).
Alternative Hypothesis = any statement which is not the null hypothesis.
*it is impossible to prove our experimental hypothesis correct but we can disprove our null hypothesis*
*2 types of experimental hypothesis:
1. Directional Hypothesis: predicts the direction of the effect e.g. the more alcohol a person
consumes will result in them demonstrating more aggressive behaviour
2. Non-directional Hypothesis: predicts an effect but not the direction e.g. the amount of alcohol a
person consumes will have an effect on aggressive behaviour
Once null and alternative hypotheses have been written, the researcher has to operationalise their
variables. This is the process of devising a way of measuring a variable. E.g. For digit recall
defining what `reading out loud' was, and what was meant by `sub-vocal'. And also identify how
this would be observed and measured each of these variables.
Next step: carry our research investigation which will generate data which will be analysed. This
determines if the results verify or refute the research hypothesis.
Theories = a complex set of interrelated statements that, when taken together, offer a way of
explaining a phenomena.
Variable: a measure characteristic or value can differ from one observation to another.
Experiment: research investigation in which one specific variable is manipulated to observe its
effect, if any, on another specific variable while keeping all other variables controlled.
Reliability and validity
Reliability means that two or more measurements or observations of the same psychological event
will be consistent with each other.
Validity means that we are actually measuring what we claim to be measuring. There are two broad
Internal validity = if the outcome is the result of the variables that are manipulated in the study.
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External validity = the extent to which findings can be generalised to settings other than the
research settings. Population validity whether the findings can be generalised to other people.
Ecological validity whether the results can be generalised to other settings.
*Different methods are used to measure validity, such as intelligence tests and personality tests.*
METHOD OF ASSESSING VALIDITY EXPLANATION
FACE VALIDITY THIS IS THE MOST BASIC METHOD OF ASSESSING
VALIDITY AND QUITE SIMPLY INVOLVED AND `EYEBALL