MEASUREMENT AND DATA ANALYSİS

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

Psychologist can measure unlimited number of behaviors to observe the psychological construct in question overt behavior (e.g., rats running through a

maze) self-report (e.g., college students filling out an

attitude survey) to recordings of physiological activity (e.g., blood

pressure, galvanic skin response)

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

Attention Span A study on ‘‘span of apprehension in

schizophrenic patients as a function of distractor masking and laterality’’ (Elkins, Cromwell, & Asarnow, 1992) investigated attention-span limitations in patients diagnosed with schizophrenia. The behavior measured was whether or not the participants could accurately name the target letters in different circumstances. Compared with nonschizophrenic controls, the schizophrenic patients did poorly when asked to identify target letters appearing in an array of distracting letters.

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

Burnout A study on the ‘‘effects of respite from work on

burnout: vacation relief and fade-out’’ (Westman & Eden, 1997) looked at the effects of a vacation on perceived stress and degree of burnout for clerical workers in an electronics firm. On three different occasions, before, during, and after a vacation, researchers measured (a) perceptions of job stress with eight items from a survey instrument called the ‘‘Job Characteristics Questionnaire,’’ and (b) job burnout with a twenty-one-item ‘‘Burnout Index.’’ Participants also filled out a ‘‘Vacation Satisfaction Scale.’’ Initially, high stress and burnout scores dropped precipitously during the vacation, but the effect was very short-lived. By three weeks after the vacation, stress and burnout levels were back at the pre-vacation level.

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

Honesty A study on the ‘‘effects of deindividuation on

stealing among Halloween trick-or-treaters’’ (Diener, Fraser, Beaman, & Kelem, 1976) observed the candy- and money-taking behavior of children in a field study during Halloween night. The behavior observed (from behind a screen by an experimenter) was whether children took extra amounts of candy, and/or took money that was in a nearby bowl, when the woman answering the door briefly left the room. When given an opportunity to steal, the children were most likely to succumb to temptation when (a) they were in groups rather than alone, and (b) anonymous (i.e., not asked their name) rather than known.

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

Arousal A study of ‘‘task-related arousal of Type A and

Type B persons’’ (Holmes, McGilley, & Houston, 1984) compared two types of subjects (A and B) on a digit span task (listen to a list of numbers, then repeat them back accurately) that varied in difficulty. While performing the task, several physiological measures of arousal were taken, including systolic and diastolic blood pressure. Compared with more laid-back Type B subjects, hard-driving type A subjects showed elevated blood pressure, especially when the task increased in difficulty.

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

How a researcher decide on a certain measure, instead of others, to make a psychological construct observable Previous studies Modifying comonly used measures Be creative: use an old measure for a new

construct By this way, psychologist can study even

seemingly unemprical questions Do preverbal infants understand the concept of

gravity? Can you demonstrate that people use visual

images?

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

Research Example 1—Habituation Do preverbal infants understand the concept

of gravity? We know that infants do “preferential looking”

and habitation preferential looking: infants prefer to look at events

that are new to them (Spelke, 1985) Habituation: When a stimulus is presented repeatedly,

infants lose interest (i.e., they stop looking)

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

Research Example 1—Habituation Kim and Spelke (1992) compared 5- and 7-

month-olds in terms of their understanding of gravity

Two Things New1. Going up2. Slowing Down

OneThings New1. Going up

WHAT TO MEASURE—VARIETIES OF BEHAVIOR

Research Example 2—Reaction Time Can you demonstrate that people use visual

images? Shepard and Metzler (1971) asked participants to

decide whether each right-hand object of each pair be the same as the left-hand object, but merely rotated to a different position

EVALUATING MEASURES

How can we decide if one measure is better than others? Reliability

It is about whether measurements are consistent in repeating remeasures

Validity It is about whether the measurement measures what is

aimed to be measured

EVALUATING MEASURES

All the variability in the DV scores

Variability in DV caused by

the IV

Variability in DV caused by error

This is spread randomly across the

scores of both conditions

This affects the scores of one

condition differently from the other

Random error

Systematic error

Systematic error

EVALUATING MEASURES

Reliability: Consistency in Measurement Inconsistent Measures

RT1= 850ms, RT2=370ms, RT3=1120ms Consistent Measures

RT1= 850ms, RT2=860ms, RT3=840ms

Two Kinds of Reliability Consistency in Time Internal Consistency

Reliability is a statistical question.

EVALUATING MEASURES

Validity: Measuring what we want to measure Validity is a theoretical question

A single study is not enough to decide whether a measure is valid or not.

EVALUATING MEASURES

Types of Validity Face Validity: Do the outlook of the measurement

look valid? Content Validity: Are the items or tasks of the

measurement valid? Criterion validity: Are the measures consistent

with a already known valid measure Predictive Validity: Can measure predict future

behavior? Construct Validity: Can the measure in question

measure the psychological construct Convergent Validity Divergent Validity

EVALUATING MEASURES

Bandura (1986): self-efficacy: judgments of [our] capabilities to

organize and execute courses of action required to attain designated types of performances

Locus of control (LOC) concerns our personal beliefs about the causes of what happens to us

self-confidence: Confidence is a nondescript term that refers to strength of belief but does not necessarily specify what the certainty is about. 

EVALUATING MEASURES

Mayer & Frantz (2004): Connectedness to Nature Scale (CNS) Sample items

I think of the natural world as a community to which I belong I have a deep understanding of how my actions affect the

natural world My personal welfare is independent of the welfare of the

natural world For Construct Validity

CNS NEP (‘‘New Ecological Paradigm’’) scale Ecological behaviors

(e.g., how often they turned off the lights in vacant rooms), Scholastic aptitude: SAT a measure of social desirability

(scoring high on this test means wanting to make oneself look good)

SCALES OF MEASUREMENT

We are quite familiar with four kinds of scales Nominal Ordinal Interval Ratio

Let’s work on some examples to get sure that you got the idea

SCALES OF MEASUREMENT Comparing male and female joggers, who is more likely to run

during the morning and who is more likely to run in the evening? If a child ranks five toys and is given the one ranked third, will

the ranking for that toy go up or down after the child has played with it for a week?

Jesse is interested in sex differences in shyness and gives a 15-item shyness test to groups of men and women. Each item has a statement (e.g., I have difficulty talking to strangers) that asks responders to rate on a scale from 1 (strongly disagree) through 5 (strongly agree).

How do young versus old people rank ten movies that vary in the levels of the amount of sex and aggression found in them?

When you change answers on a multiple-choice test, are you more likely to improve your score or hurt it? Kruger, Wirtz, and Miller (2005)

right → wrong: 25% Wrong → right: 51% wrong → wrong: 23%

STATISTICAL ANALYSIS

You are very familiar with these issues, so I assume that you can answer any question related to statistics correctly in the exam