Week 1: Introduction to Measurement in Research

• Non-scientific methods of understanding include tenacity (belief perseverance), intuition, authority, rational method, and empiricism (observation).
• Psychology uses the scientific method to objectively study behaviour and the mind/brain, aiming to eliminate bias, expectations, and mood influences.
• Science operates as an error-detection mechanism, discarding flawed ideas through critical logic and empiricism (knowledge gained through experience).

Steps in the Research Process

• Research begins with a question stemming from an observation or idea, probing why something occurs.
• Review existing theories and literature to formulate a hypothesis.
• Identify the variables to be measured and those to be manipulated.
• Determine the participant group.
• Select a research strategy.
• Choose a research design.
• Collect data through measurement.
• Analyze data to test the hypothesis.
• Evaluate and update the theory based on findings.

Establishing a Research Question

• Select a broad topic.
• Review existing literature.
• Ensure the topic is interesting, achievable, practical, ethical, and aligned with long-term interests.

From Theory to Hypothesis

• The 'Hypothetico-deductive model' involves deducing specific hypotheses from a theory.
• A hypothesis must be logical, testable, falsifiable, and positive (directional or non-directional).

Defining and Operationalising Variables

• Defining variables specifies what will be measured.
• Operationalising variables determines how it will be measured using surveys, scales, or custom tools.
• New measures must possess reliability and validity.

Identify Participants

• Define the target population.
• Ensure the sample aligns with the theory.
• Acknowledge limitations due to sample bias, such as WEIRD samples, or practical constraints.

Select a Research Strategy

• Correlational methods describe what is happening.
• Experimental methods explain underlying causes.

Correlational Method

• Assesses the relationship between two variables, including linear or non-linear relationships, strength, and direction (positive/negative).

Experimental Method

• Manipulates an independent variable (IV) to observe its effect on dependent variables (DV).
• Compares treatment/experimental conditions with a control condition.
• Extraneous variables are all other variables in a study that aren't being manipulated, while confounding variables influence the DV.

Importance of Measurement

• Measurement is crucial for scientific research.
• Psych involves designing and evaluating instruments and is difficult.
• Used in clinical practice to diagnose and decide on treatment/intervention

Two Sources of Measurement Error

• There are two types of measurement error, these may interact to create uncertainty when measuring

Random Error

• Random errors include human mistakes.
• Incorrect measurement tools (stochastic) can lead to random errors.
• Slight differences in an instrument, environment, or reading conditions.
• Decreases chance of significant results, possibly leading to a Type II error.

Systematic Error

• Systematic errors are measurement errors consistenly departing from the true value.
• Introduces bias, potentially leading to Type I error (false positive) or Type II error.

Precision vs. Accuracy

• Precision is the consistency of repeated measurements - low precision reflects random error.
• Accuracy is the conformity of a measurement to its true value - low accuracy reflects systematic error.