Psychological research methods

Methods for defining questions, obtaining observations and evaluating claims in psychology. Design of experiments can identify effects of assigned conditions; an observational study measures existing variation. Qualitative research methods examine meanings and processes in context. The method must fit the question and the intended inference.

Dense repeated observation around a period of learning or change. Trial-level behavior can reveal transitions missed by widely separated tests, although the measurements themselves may influence learning.

A randomized study of a supported foster-care intervention for young children already living in institutions. The randomized offer supplies evidence about changing care; subsequent care changes, adherence and attrition affect the estimand and analysis. Mediator claims about attachment need assumptions beyond randomization of the whole package.^[ref]

Collecting repeated reports about ongoing experience in ordinary life. Frequent reports reduce some retrospective demands, but are still measurements with selection, response and reactivity issues. An observed association is not automatically a randomized causal effect.

A change associated with treatment context or expectation rather than the specific active component being tested. A comparison with no treatment and appropriate masking is needed to distinguish a placebo effect from spontaneous change or reporting differences.

A belief about the likely consequences of treatment that can influence attention, interpretation, behaviour and symptom experience. Experimental changes in expectation at constant drug exposure can distinguish contextual modulation from differences in administered dose.^[ref]

An intervention transparently described as inert rather than concealed as an active medication. Trials require an appropriate comparator and must address unblinded reporting, explanatory rationale and duration; an effect for one symptomatic outcome is not a universal disease-modifying benefit.^[ref]

The observed change after placebo administration, including possible contextual effects, spontaneous change, regression to the mean and concurrent care. A placebo group's improvement is not by itself an estimate of the causal placebo effect.

Adverse change attributable to a negative treatment context or expectation. It can involve genuine discomfort and physiological modulation as well as reporting and attribution. Its presence does not exclude concurrent disease or a direct adverse drug reaction.^[ref]

A reduction in pain associated with a placebo manipulation. Its influence on responses to others' pain can test shared modulation, without showing that the two experiences have identical neural representations.

Estimating which stimulus variations systematically accompany an observer's responses. Randomly varying facial movements and correlating them with emotion judgments can reconstruct response-relevant features, conditional on the stimulus space and judgment task.

The extent to which an intervention is delivered as intended, including relevant procedures, dose and competence. A trial's success under expert support does not by itself establish the same effects under routine delivery.

Principles and practices for responsible research, including respect for participants, scientific integrity, proportionate risk assessment and independent review. Informed consent, privacy and honest reporting are part of the research design rather than substitutes for its scientific quality.^[ref]

Time, effort, discomfort or disruption associated with research or intervention. A low therapist-time programme can still impose substantial burdens on caregivers and children.

Protection against inappropriate identification or disclosure of participant information. Data sharing should reflect consent and the identifying content of the material; identifiable child video may require controlled access rather than public release.

An explanation after participation of the study's purpose and relevant procedures, including justified deception, with an opportunity for questions and appropriate follow-up. Its form should fit what participants experienced and the study's risks.

Intentionally misleading participants or withholding relevant information about a study. Its necessity and risks require justification and appropriate review; less deceptive alternatives should be considered. Research debriefing can explain what was withheld but does not automatically remove all consequences.

Approaches to investigating meaning, experience and processes through material such as interviews, observations and documents. Explain the sampling rationale, analytic approach and path from evidence to interpretation. Quality criteria should fit the approach rather than mechanically importing every criterion of a statistical survey.

Critical consideration of how the researcher's position, assumptions and interactions influence the questions, material and interpretations. A reflexive record helps make these contributions inspectable; it does not claim that the researcher can remove every influence.

Selecting cases because their characteristics or experiences are informative for a specified research question. It can deliberately include contrasting roles or experiences; it does not imply probability-based population representation.

Systematic interpretation of recorded material using an explicit categorization process. Categories can be developed from theory, the material or both. State how categories were developed and applied and how evidence supports the resulting claims.

Analysis identifying and interpreting patterns of meaning in qualitative material. The researcher should state the theoretical and analytic approach, explain the development of themes, and support interpretive claims with contextualized evidence.

The elapsed time between a specified event and a response. The event, response criterion and time units must be defined; trial exclusion and aggregation affect its analysis. Repeated trials from one participant are not independent participant-level observations.

A relationship in which changes in response caution or time allocation affect both speed and error rate. A faster mean response is not automatically better performance if accuracy also falls; both measures and their uncertainty should be examined.

A model in which separate sensory channels can each trigger a response, and the first completed channel determines response time. Context invariance means that a channel's marginal completion distribution is unchanged between its single-signal and redundant-signal conditions. Independence is a separate, stronger assumption.

Under context-invariant channel distributions, $P(\min (T_A,T_V)\le t)=P(T_A\le t\mathrm{or}{T}_V\le t)\le F_A(t)+F_V(t)$ by the union bound; probability is also at most one. No independence assumption is needed. A reliable violation rejects this model with those marginals, not every possible separate-channel or decision account.