chapter 3: constructs and operational definitions

variables

characteristics or conditions that change or have different values for different individuals

theory

set of statements about mechanisms underlying a particular behaviour

constructs

hypothetical entities created from theory and speculation

• cant be seen but assumed o exist

operational definitions

methods of defining and measuring constructs

• help assign numbers to hypothetical constructs but does not mean “nothing”

validity and reliability

defined and measured by the consistency of the relationship between two sets of measurements

positive relationship

the 2 measures change together in the same direction

• correlation near +1.00

negative relationship

the 2 measures change in opposite directions

• correlation near -1.00

correlation for an inconsistent relationship

near zero

when establishing validity, measurement must accurately capture

the variable that it is intended to measure

face validity

simplest and non-scientific

• an environment that makes the participant feel as if they are in the type of environment we are experimenting

  • eg: for kids, environment needs to resemble a daycare or classroom

concurrent validity

scores that come from a new measure

• needs to be a close measurement between the new measurement tool and old measurement tool

predictive validity

scores obtained from a measure accurately predicts behaviour according to a theory

construct validity

scores obtained from a measurement behave exactly the same as the variable itself

construct validity

scores from different experiments are strongly related to ours

divergent validity

showing little or no relationship between the measurements of two different constructs

• opposite of convergent validity

reliability

stability or consistency of the measurements produced by a specific measurement procedure

observer error

the individual who makes the measurements can introduce simple human error

environmental changes

difficult to attain the ideal identical circumstances

participant changes

participant can change between measurements

• eg: degree of focus

test-retest reliability

compares scores of two successive measurements of the same individuals and correlates the score

• parallel forms reliability

inter-rater reliability

agreement between two observers who simultaneously record measurements of the behaviours

split-half reliability

splits the test in half, computing a separate score for each half, then calculates the degree of consistency between two scores for a group of participants

measurement

the process of assigning values meaningfully to behaviour, people, attributes, etc

goal of measurement

assign numbers to the variable of interest

identity

each number has a unique meaning

magnitude

numbers have an inherent order

equal intervals

difference between units is the same anywhere on the scale

true zero

zero on the scale is a true zero, no variable detected

nominal variables

levels are qualitatively distinct categories that have no true quantitative or numerical properties

ordinal scale of quantitative variables

numbers represent rank ordering

• higher number represent more of the quality being measured

distances between consecutive values are not equal

intervals of quantitative variables

distances (intervals) between consecutive values are equal

no true zero point

ratio of quantitative variables

equal intervals and a true zero point (means nothing)

considerations before choosing a scale of measurement

• information yielded

• statistical analyses

• ecological

types of measurement

• self-report

• observational (behavioural)

• physiological

self-report

involves having people tell you about themselves

• questionnaires and interviews

observational methods

involves the direct observation of behaviour

• limitation: behaviours can subjective to an underlying construct

physiological measures

involves measuring a bodily process

• provide objective measures

• limitations: may require equipment, ethics

choosing types of measures

guided by theoretical interest

• actual abilities vs. perceptions

benefits of using multiple measurements

provide more confidence in measurements

limitations of using multiple measurements

• more complex statistical analysis and interpretation

• lack or agreement between two measures

method for limiting problems when using multiple measures

combine the measures into a single score for each individual

range effect

a measurement that is not sensitive enough to detect a difference

ceiling effect

clustering of scores at the high end of a measurement scale

• little or no possibility of increase in value

floor effect

clustering of scores at the low end of a measurement scale

• little or no possibility of decreases in value

artifact

a nonnatural feature accidentally introduced into something being observed

experimenter bias

measurements are influenced by the experimenter’s expectations regarding the outcome of the study

how to limit experimenter bias

• single-blind study

• double-blind study

single blind study

the research study is conducted on a participant who does not know the expected results

double blind study

neither the participant or experimenter know the expected results of the study

demand characteristics

refer to any of the potential cues or features of a study that may influence the participants to respond or behave a certain way

reactivity

when participants modify their natural behaviour in response to knowing they are in a study 

• stanford prison experiment

good subject role

supports the experimenter

s hypothesis

negativistic subject role

acts contrary to the hypothesis

apprehensive subject role

presents self in a good light

faithful subject role

follows instructions to the letter (ideal participant)