Data collection, analysis and evaluation (science inquiry): WACE Year 12 Psychology

What this dot point is asking

This page covers the second half of the Science inquiry strand, which is examined in both units. For aims, variables, designs and sampling, see research methods.

Types of data and how they are collected

• Structured interviews use the same fixed questions in the same order for everyone; semi-structured interviews have set questions but allow follow-up questions.
• A focus group interviews several people together; an individual interview is one-on-one.
• Galvanic skin response (GSR) measures changes in the skin's electrical conductance caused by sweating, an indicator of arousal.
• A Likert scale asks people to rate agreement with a statement, for example from 1 (strongly disagree) to 5 (strongly agree).
• Mixed methods combine qualitative and quantitative data in one study.

Subjective and objective data

• Objective data are measured independently of anyone's opinion, such as heart rate or reaction time. They are less open to bias.
• Subjective data are based on the participant's own judgement or report, such as a stress rating or an interview answer. They show personal experience but can be affected by memory, honesty and demand characteristics.

Displaying data

Every graph needs a title, labelled axes with units, the IV on the x-axis and the DV on the y-axis.

Mean and median

• Mean: add all the scores and divide by the number of scores. It uses every score but is pulled by extreme values.
• Median: the middle score when scores are placed in order. With an even number of scores, it is the average of the two middle scores. It is not affected much by extreme values.

Pearson's correlation coefficient

Pearson's correlation coefficient (r) describes the strength and direction of a linear relationship between two variables.

• r ranges from -1 to +1.
• The sign gives the direction: positive (both increase together) or negative (one increases as the other decreases).
• The size gives the strength: values close to 1 or -1 are strong; values close to 0 show little or no linear relationship. A common rough guide is about 0.1 to 0.3 weak, 0.4 to 0.6 moderate and 0.7 to 0.9 strong.
• Correlation does not show causation: a third variable, or a relationship in the opposite direction, could explain it.

Drawing conclusions and evaluating research

• Conclusion: state whether the results support the hypothesis, refer to the data, and answer the research question. Do not go beyond the sample and design.
• Validity: whether the study measured what it intended to measure, and whether the change in the DV was caused by the IV rather than extraneous variables.
• Reliability: whether the results are consistent if the study is repeated.
• Generalisability: whether the sample represents the population, so the results can be applied to it.
• Improvements: specific changes that fix a named limitation (a larger, stratified sample; standardised instructions; an objective measure).
• Ethical implications: how the guidelines were or were not met.
• Critical evaluation of sources: judge where information comes from, such as peer-reviewed research versus opinion or advertising.
• Communicating: use psychological terminology and acknowledge sources with appropriate referencing.