Scientific Processes? Flashcards
What does aim mean?
statement about what the study is trying to achieve
What does experimental/alternative hypothesis mean?
Predicts that differences in the DV will be beyond the boundaries of chance (they will occur as a result of manipulation of the IV).
Differences beyond the boundaries of chance are significant differences and this can be incorporated into a hypothesis.
For example, ‘caffeine consumption will significantly affect reaction times’. Statistical tests are used to see if results are significant (see page 334). The term ‘experimental hypothesis’ is only used with the experimental method. Other research methods use the term ‘alternative hypothesis’, but the definition is the same.
Null Hypothesis?
Is ‘the hypothesis of no differences’. It predicts that the IV will not affect the DV. Any differences in results will be due to chance factors, not the manipulation of the IV, and will therefore be not significant and this can be incorporated into a null hypothesis.
For example, ‘there will be no significant difference in reaction times as a result of caffeine consumption’.
One of the two hypotheses, null or experimental, will be supported by the findings and thus be accepted, with the other one being rejected.
Hypothesis?
Testable prediction of what is expected to
happen
Dependent Variable?
Variable that is manipulated by the experimenter.
In an experiment on the impact of sleep deprivation on test performance, sleep deprivation would be the independent variable. The experimenters would have some of the study participants be sleep-deprived while others would be fully rested.
Independent Variable?
Variable that is measured by the experimenter. In the previous example, the scores on the test performance measure would be the dependent variable.
What are the two types of experimental hypotheses and what do they mean?
- Directional (‘one-tailed’) hypothesis - predicts the direction of the results. For example, there will be a significant reduction in the speed of reaction times as a result of caffeine consumption’. It gets its name from predicting the direction the results will go.
- Non-directional (‘two-tailed’) - predicts that there will be a difference, but does not predict the direction of the results. For example, ‘there will be a significant difference in the speed of reaction times as a result of caffeine consumption’. Reaction times will be either quicker or slower.
When is directional hypothesis used?
Directional hypotheses are used when previous research suggests that results will go in one direction, or when replicating a previous study that also used a directional hypothesis.
What is sampling?
What should it be ideally?
What does target population mean?
Testing part of the population, Psychologists use different sampling techniques such as random sampling
Ideally a sample is representative (contains the same characteristics as the population from which it was taken)
The term target population is used to indicate the group of people the results are targeted at.
What is random sampling?
What is one way it can be achieved?
What does it result in?
Random sampling is where each member of a population has an equal chance of being selected.
One way to achieve this is to place all names from the target population in a container and draw out the required sample number, while computer programs are also used to generate random lists.
This results in a sample selected in an unbiased fashion.
What are 2 strength and 2 weaknesses of Random Sampling?
Strengths of random sampling
- Unbiased selection - there is no bias in selection, increasing the chances of getting an unbiased and thus representative sample.
- Generalisation - as the sample should be fairly representative, results will be generalisable to the target population.
Weaknesses of random sampling
- Impractical -random sampling is difficult to achieve, as it is sometimes difficult to get full details of a target population and not all members may be available or wish to take part.
- Not representative - unbiased selection does not guarantee an unbiased sample; for example all females could be randomly selected, making the sample unrepresentative and thus the results not generalisable.
What does sampling techniques, generalisation and bias mean?
Sampling Techniques- Various methods of selecting samples of participants from target populations
Bias - the degree to which participants in a sample have been selected without prejudice
Generalisation - the extent to which findings generated from a sample are representative of a target population
Opportunity Sampling?
Opportunity sampling involves selecting participants who are available and willing to take part, for example asking people in the street who are passing. Sears (1986) found that 75 per cent of university research studies use undergraduates as participants, simply for the sake of convenience.
2 strengths and 2 weaknesses of Opportunity Sampling?
Strengths of opportunity sampling
- Ease of formation - opportunity samples are relatively easy to create, as they use people who are readily available
- Natural experiments - with natural experiments opportunity sampling usually has to be used, as the researcher ha no control over who is studied.
Weaknesses of opportunity sampling
- Unrepresentative - the sample is likely to be biased by excluding certain types of participants and thus be unrepresentative, so that findings cannot be generalised to the target population. An opportunity sample collected > town during the day on a week day would not include those at work or college.
- Self-selection - participants have the option to decline to take part and the sampling technique thus turns into a self-selected sample.
Volunteer (self-selected) sampling
Volunteer/ Self Selected Sampling?
Volunteer or self-selected sampling involves people volunteering to participate. They select themselves as participants, often by replying to adverts.
