Psych 311 Unit 2 study guide

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1

Validity: definition, types, difference between types, ability to determine which types of validity evidence would be most salient/important for different types of research questions

Definition: Does the instrument measure what it is supposed to measure?

- Face: Does the instrument appear to measure the construct that it claims to measure. Example: An instrument assessing sleep includes questions about sleep.

- Concurrent: Scores from one instrument are related to scores from another instrument measuring the same variable, given at the same time. Example: A new instrument measuring intelligence classifies students in the same way as standardized IQ tests given in the same time period

- Predictive: Scores on an instrument accurately predict behavior or a score in the future. Example: SAT scores predict first year college GPA

- Construct: Measurements of a variable behave in the same way as the variable itself. Example: Feminists describe themselves as endorsing specific beliefs that are also endorsed on your measure of feminism

- Convergent: Strong relationship between the scores of two different measures used to measure the same construct. Example: Teacher ratings and observational scores for child aggression in schools

- Divergent: Little or no relationship between the scores of two different constructs when measured with the same method. Example: Teacher and observational scores for child activity level and aggression are separate and distinct

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Reliability: definition, role of error, sources of error, systematic vs random error, be able to explain how the number of items in a scale impacts reliability

Definition: Does the instrument measure something consistently?

Sources of error: observer error, environmental changes, participant changes

Random error: Caused by unpredictable fluctuations & inconsistencies in the measurement process (e.g., earthquake, fire alarm, spider dropping onto your desk)

Systematic error: Typically constant or proportionate to what is presumed to be the true value of the variable being measured (e.g., your scale is off by 2 pounds, but it is always off by 2 pounds)

As the number of items in a scale increases, reliability also increases

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Types of reliability

Successive

- Test-retest: A type of successive reliability in which the researcher/evaluator compares scores from two measurements of the same person

- Parallel forms: A subtype of test-retest reliability in which two versions of the same test are given to the same person at different times to see if the measurements are (enough) the same

Simultaneous

- Inter-rater: Degree of agreement between two observers who simultaneously record measurements of participant behaviors

- Split-half: A measure of internal consistency, Splitting a questionnaire in half (not necessarily 1st half and second half), computing a separate score for each half, and determining the correlation of the two scores

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interpretation of reliability scores, questions about example reliability scores

Correlation coefficients: A numerical value that measures or describes the relation between two variables, typically represented by r

- The direction of relation: +/-

- The form of relation: indicated by type (pearson or spearman)

- Strength or consistency of relation: -1 to +1, 0=no relation

- Degree of relation r2

- Small: r=.1 or r2=.01

- Medium: r=.3 or r2=.09

- Large: r=.5 or r2=.25

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Relationship between reliability and validity

card image

Reliability is simple therefore it is reported more often, also if measure is not reliable then it cannot be valid

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Find, identify, interpret information about psychometrics of measurement instruments in the method section of an empirical article

...

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Experimenter bias

When measurements obtained in a study are influenced by the experimenters expectations or personal beliefs regarding the outcome of the study

Single-blind: PARTICIPANT does not know predicted outcome (note this is different from your textbook information)

Double-blind: Researchers and participants are BOTH unaware of predicted outcome

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Demand characteristics

Features of the study that suggest to the participant what the purpose and hypothesis of the study is and influence the participants to respond a certain way

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Reactivity and reactivity reduction

Reactivity occurs when participants modify their behavior in response to the fact that they are being measured

To reduce reactivity:

- Observe without participant awareness

- Disguise questions

- Use deception

- Reassure participants that answers are confidential and anonymous

10

Hawthorne studies

Attempt to study what conditions in a factory modified worker behavior but ALL study variables improved worker productivity, because the process of being observed made workers more aware of their work

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Subject roles

- Faithful: Follow instructions, don’t modify responses in any way based on hypothesis of what the study is about

- Apprehensive: Socially desirable responses, want to look good and give responses they think will make a good impression

- Negativistic: Respond in a way that they think will specifically contradict the researchers’ hypothesis

- Good: Trying to be helpful, respond in a way that they think will most help the researcher get the data they need/want