Key Science Skills

Population

The larger group of people that a researcher wishes to study.

Sample

A smaller subset of the population chosen to participate in the study.

Generalisability

The ability for a sample’s results to be applied to the wider population.

Convenience Sampling

Selecting readily available participants without a random or systematic approach.

Random Sampling

A technique ensuring every member of the population has an equal chance of being selected.

Stratified Sampling

A technique where the population is divided into strata (subgroups), and participants are selected in proportion to their representation.

Extraneous Variable

A variable other than the independent variable that may affect the dependent variable.

Confounding Variable

A variable that has directly and systematically affected the dependent variable apart from the independent variable.

Participant-related variables

Differences in participants (e.g., age, background) that affect results.

Order effects

When the sequence of experimental tasks affects performance.

Placebo effect

When participants respond to an inactive treatment due to expectations.

Situational variables

Environmental factors affecting results (e.g., weather, time of day).

Experimenter effects

Researcher bias influencing results.

Non-standardised instructions and procedures

Differences in how participants are instructed.

Demand characteristics

Participants altering behavior based on perceived study aims.

Counterbalancing

Alternating the order of conditions to reduce order effects.

Single Blind Procedure

Participants do not know which group they are in.

Double Blind Procedure

Both participants and experimenters do not know who is in which group.

Standardised Instructions and Procedures

Ensuring uniformity in instructions and processes.

Primary Data

Collected first-hand by a researcher.

Secondary Data

Data obtained from previous research.

Qualitative Data

Non-numerical data (e.g., descriptions, feelings).

Quantitative Data

Numerical data (e.g., test scores).

Objective Data

Measurable and not influenced by personal bias (e.g., IQ scores).

Subjective Data

Based on personal opinions or perceptions (e.g., self-reports).

Mean

The numerical average of a dataset.

Median

The middle value in an ordered dataset.

Mode

The most frequently occurring value in a dataset.

Range

The difference between the highest and lowest values in a dataset.

Standard Deviation

A measure of how much values deviate from the mean.

Accuracy

How close a measurement is to the true value.

Precision

How close repeated measurements are to each other.

Systematic Error

Consistent error affecting all measurements (e.g., faulty scale).

Random Error

Unpredictable errors that vary from measurement to measurement.

Internal Validity

The extent to which a study truly measures what it claims to.

External Validity

The extent to which results can be applied to different settings.

Ethical Concepts

Broad moral principles guiding research.

Ethical Guidelines

Formal rules researchers must follow to ensure ethical standards.