Quiz 4 Psyc 2018 variables, falsification, operational definitions

Quantitative research

scientific method to record observations as numeric data

describe, interpret, and explain behavior(s) or event(s) being studied (interviews and observations)

Reaction time / accuracy

Variables

Something that varies

Behaviour varies

Observable

Replicable

qualitative variable

varies by amount

Continuous (calories or time)

Discrete (pieces or segments)

varies by class

Labels

SES / political affiliation / psychological traits

Measuring Behaviour

Deciding how to measure comes from three sources:

1. using the same measures as other researchers

2. modifying other measures

3. refining the constructs of interest

Measurement

process of assigning symbols to objects or events according to rules

Scales of Measurement

measurement differ according to how they accommodate the following properties of real numbers.

(a) numbers are in any order

(b) differences between pairs may be ordered

(c) number series has an origin value at zero

Four scales of measurement 

Nominal, Ordinal, Interval, Ratio

What is the scale’s ability in comparing different measurements?

Nominal: reveals whether a difference exists

Ordinal: indicate the direction of the difference (which is more and which is less)

Interval: determines the direction and the magnitude of a difference

Ratio: determines the direction, magnitude, and ratio of a difference

Nominal

1. no properties of real numbers

2. number or name assigned to person or thing

3. assignment is arbitrary

4. no quantitative characteristic sallows categorization

Ordinal

rank order events

Ordinal with zero point

special case: scale created with neutral centre point Example: respondents rate approval-disapproval using:

3 2 1 0 +1 +2 +3

⇑

zero point represents a neutral rating

Interval

1. equal intervals between numbers on scale

2. no ratio statements can be made

Example: inappropriate to say IQ of 100 is twice as intelligent as IQ of 50

Ratio

1. true zero point

2. ratio statements can be made

Example: the 10 year old was twice as fast (1 min.) at solving the problem as the 4 year old (2 min.

Dealing With Equivocal Measurements

Interval or ratio scale scores are:

Compatible with basic arithmetic

Suitable for statistical analysis (e.g., mean and variance) ►allow hypothesis testing.

Distinction between interval and ratio measures is not always clear cut

Operational Definitions of variables 

Construct: an abstract concept that must be translated into concrete forms of observation or manipulation

Example: hunger, intelligence, aggression

Many ways to operationalize the same construct

Defines the operations or techniques the researcher will use to measure or manipulate a variable.

Necessary for empirical study

Help communicate ideas to others

Methods of defining and measuring constructs

Variables that cannot be observed or measured directly

Examples:

Intelligence can be operationally defined as a score on an IQ test; Hunger can be operationally defined as the number of hours of food deprivation. Happiness –a feeling of euphoria / accomplishment. A lack of anxiety. A low resting heartrate, normal bp.

Stress

Self rating (level of worry / tension)

Psychological measures of stress (questionnaires; rating scales)

Frequency of nervous habits (fidgeting, nailbiting)

Physiological measures (GSR, heart rate blood pressure)

Situational demands (easy / difficult task)

Limitations of Operational Definitions

An operational definition is not the same as the construct itself.

Concerns about the quality of operational definitions and measurements produced

It is easy for operational definitions to leave out important components of a construct.

Operational definitions often include extra components that are not part of the construct being measured.

Dependent Variables DV

what is measured

Independent Variable IV

controlled &manipulated by experimenter

Using Operational Definitions

Consult previous research to determine the best way to measure a variable.

Use the conventional way of measuring a variable so that your results can be compared to previous studies

Converging operations & replication

studies using different operational definitions of a phenomenon lead to same conclusions

Example: neuropsychological studies of normal brains & those with brain damage lead to similar results.

Modalities of Measurement

Behavioral measures are based on overt behaviors that can be observed and measured.

Provide researchers with a vast number of options Possible to select the behavior(s) that seems to be best for defining and measuring the construct

Behaviors may be only a temporary or situational indicators of an underlying construct.

Self report measures ask participants direct questions to study behavior. Provides a direct measure; validity is dubious

Physiological measures are based on manifestations of the underlying construct.

Other Aspects of Measurement

Multiple measures provide more confidence in the validity of the measurements.

Problems - Complex statistical analysis and interpretation Lack of agreement between two measures

Solution - Combine the measures into a single score or each individual

Range Effects 

a measurement that is not sensitive enough to detect a difference 

Ceiling Effect 

clustering of scores at the high end of a measurement scale

Allowing little or no possibility of increases in value

Floor effect

clustering of scores at the low end of a measurement scale

Allowing little or no possibility of decreases in value

Non-experimental Method:

no manipulation of variables, description of behavior

Correlational method: measure covariation between two variables •No manipulation, just observation = no causation •Direction & strength

Experimental Method

manipulation of variables, explanation of behavior

•Can make causal statements •Can establish temporal precedence •Attempt to eliminate alternative hypotheses •Experimental control & random assignment = eliminate confounds

Experimental method issues

Artificiality of experiments

Ethical and practical considerations

Participant variables cannot be manipulated

Causation or description or prediction

Interpreting non-experimental results 

Cannot make causal statements

Cannot establish temporal precedence

Also there is the “Third-Variable” problem

Artifact

nonnatural feature accidentally introduced into something being observed

Experimenter bias

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

Single blind study

The research study is conducted by an experimenter who does not know the expected results

Double blind study

Neither the experimenter nor the participants know the expected results of the study

Demand characteristics

refer to any of the potential cues or features of a study that:

suggest to the participants the purpose and hypothesis of the study, and

influence the participants to respond or behave in a certain way

Reactivity

Participants modify their natural behavior in response to knowing they are in a study

Demand Characteristics and Participant Reactivity

Good subject role

Negativistic subject role

Apprehensive subject role

Faithful role 

Good subject role

Supports the experimenter’s hypothesis

Negativistic subject role

Acts contrary to the hypothesis

Apprehensive subject role

Presents himself in a “good light”

Faithful subject role

Follows instructions to the letter (ideal participant)

Selecting a Measurement Procedure

Start by reviewing past literature. If more than one procedure exists, consider which will best answer your question. Especially consider how much sensitivity in measurement you will need.

How to Build a Graph: Dos and Don’ts

APA style: Graphing guidelines for social scientists

1. Refer to tables and figures in the text by number, and briefly describe them.

2. Place the final, camera read versions of the actual tables and figures at the end of the manuscript.

3. Provide a complete and clear caption for every figure on a separate page.

4. Write the number of the figure in pencil as close as possible to the top right of the final copy of the figure.

5. Write the manuscript’s short title and the word TOP on the back of the final copy to indicate the top of the figure.

Choosing the type of graph: understanding our variables

1. One interval variable: histogram or frequency polygon

2. One interval independent and dependent variable: scatterplot or line graph

3. One nominal independent and one interval dependent variable: bar graph

4. Two+ nominal independent and one interval dependent variable: bar graph