Psych 311 Unit 1

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Research process

1. Find an unanswered question that will serve as a research idea

2. Form a hypothesis and make predictions

3. Determine a method for defining and measuring the variables being studied


Two aspects of measurement

1. Often, there is not a one-to-one relationship between the variable being measured and measurements obtained (knowledge and performance on test).

2. There are usually several different options for measuring any particular variable and can have consequences for the outcome of a research study.


Hypothetical constructs

Research variables, usually those of interest to behavioral scientists, that are hypothetical entities creatd from theory and speculation. Ex. intelligence and motivation



Statements about the mechanisms underlying a particular behavior, help organize and unify different observations related to the behavior.

- Good theories generate predictions about the behavior



Hypothetical attributes or mechanisms that help explain and predict behavior in a theory.

- May not be directly measurable but it is possible to examine the factors that theoretically influence a construct and study the behaviors that theoretically result from a construct.


Operational definition

Specifies a measurement procedure (a set of operations) for measuring an external, observable behavior and uses the resulting measurements as a definition and a measurement of the hypothetical construct.

- IQ test as a measurement for intelligence



- Easy to leave out important components, can be reduced by including two or more different procedures to measure the same variable

- Can include extra components that are not part of the construct being measured


Observer error

Individual who makes the measurements can introduce simple human error into the measurement process


Environmental changes

Small changes in the environment such as weather and time of day from one measurement to another can influence the measurements


Participant changes

The participant can change during measurements such as degree of focus and attention


Scale of measurement

The set of categories used for classification: nominal, ordinal, interval, and ratio


Components of measurment

Set of categories and a procedure for assigning individuals to categories


Nominal scale

Categories represent qualitative differences in the variable measured that are not related to each other in a systematic way


Ordinal scale

Categories have different names and are organized sequentially

- Tells the direction of the difference


Interval and ratio scale

Categories are organized sequentially and all categories are the same size (like the inches on a ruler).

- Interval scale has an arbitrary zero point that does not indicate the absence of the variable being measured (0 degrees), tells the direction and magnitude of a difference

- Ratio scale has a zero point representing a complete absence of the variable being measured (height and weight), tells, direction, magnitude and ratio of the difference


Self-report measures

Most direct way to assess a construct but it is easy for participants to distort.


Phisiological measures

Involve brain imaging techniques that are very accurate and reliable but presence of those devices may cause participants to react differently than they would under normal circumstances


Behavioral measures

Provide researchers with a vast number of options, making it possible to select the behaviors that seem to be best for defining and measuring a construct but behavior may be only a temporary or situational indicator of an underlying construct


Multiple measures

Gives a more complete measure of a construct but the statistical techniques for evaluating the data are complex, possible desynchrony (lack of agreement between two measures)


Sensitivity and range effects

The measurement procedure must be sensitive enough tot detect the changes, and the scale of measurement must have enough different categories to allow discrimination among individuals


Range effect

The measurement procedure is insensitive to changes that may occur in one direction


Ceiling effect

When the range is restricted at the high end


Floor effect

When the range is restricted at the low end