Variables and Scales

8/3/2019 Variables and Scales

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CONCEPCION, Denise Nicole

GUERRA, Alliah Czarielle

ROSAS, Mary Rose

VELEZ, Vida Valerie



From the root word: “vary”

To change, to become different

To shed a past state and take on another at

present.Attributes:

Specific values carried by variables.

One variable can have several attributes.



In scientific experimentation, a variable

refers to a factor available for manipulationand measurement.



Independent variables

Variables which are manipulated.

Treatment, cause

Influence other variables to change

Must have at least 2 levels (variants) Manipulated variable, explanatory variable,

individual-difference variable

2 kinds! (next slide)

Dependent variables

Variables being manipulated upon

Receive treatment and respond to it

Effect, outcome

Responding variable



True Independent Variables

Subject variables

Not manipulated by the researcher Inherent within subject

Possible relation to another subject variable



Presence vs. Absence

Type of variable

Amount of Variable Experimental Manipulation



One group of research participants receivestreatment.

Another does not.

Comparison Does group receiving treatment condition differ from

group that does not? (Christensen, 1997)

Ex. The effect of chocolate on a person’seuphoric state

One group is made to eat chocolate for a givennumber of days, in controlled amounts

Another group does not eat any chocolate

Researchers tally and compare the differencebetween the two groups’ euphoric states



Vary the type of variable under

investigation. (Christensen, 1997)



Ex. Researchers want to know what the cause of depression is in overweight people from a ruralvillage who eat primarily rice or corn.

Does it correlate more strongly to their weight or to

their diet? Two possible independent variables: Weight, Diet

Subjects in a healthy mental state might be dividedinto groups of “borderline overweight” to “severelyoverweight,” and a control group of healthy-weight

people selected The groups may then be further divided into groups

that will be fed rice, and groups that will be fed corn.The results will then be compared and a conclusionwill be drawn



Of course this is just a sample experiment; otherdesigns might be more effective and it is not for

our group to cover!

Rice Corn

Severely overweightpeople

Scores for depression after

period of eating said food



Borderline overweight

people





Normal-weight people Scores for depression after






Administer different amounts of variable to

each of several groups. (Christensen, 1997)

Ex. Does increased amounts of caffeine

improve ability to focus on tasks? One group may be limited to 2 cups of coffee per

day.

Another group is made to drink 5 cups.

Still another group may be permitted to drink upto 8 cups.



Experimenter administers one specific

controlled amount to a group of individuals

and a different specific controlled amount to

a group of individuals. (Christensen, 1997) Ex. The effect of sleep on motor

coordination

Group 1: 4 hours of sleep/day in 1 week

Group 2: 8 hours of sleep/day in 1 week*

*same starting time, might be conducted in the same place



Variable: made to vary

Changes are observed and quantified

Become the basis for the derivation of a

conclusion

Constant: unchanging

To preserve consistency throughout the

experiment



Intervening variables

Not observed directly; abstract concepts

Inferrable from the relationship between

independent and dependent variable

Explains relationship between the independent

and dependent variable

e.g. learning, expectancy, cognitive structure,

group cohesiveness, intelligence, stages of dev’t,

attitudes



Moderator (Moderating) Variable

Factor measured, manipulated or selected by

experimenter to discover whether it modifies the

relationship of the IV to the observed

phenomenon

Enhance or influence the independent variable

Ex. Experiment involving 2 methods of teaching

mathematics

Students with strong reading skills do better in 1method, students with low reading skills do

better in another

Reading = Moderating variable



Controlled variables

Variables which are held constant throughout

the experiment

Consistency purposes

Failure to isolate confounding internal

validity is compromised

Extraneous variables

Variables with no effect on the outcome of theexperiment



Experimental group Subjects which receive experimental treatment

Manipulated by researcher. (Johnson and Solso,1984)

Control group Subjects given same treatment as experimental

group, but not manipulated by researcher.(Johnson and Solso, 1984)

Held constant in research study by observingonly one of its levels. (Shardson, 1988)

Used to neutralize the effects of variables not of central focus to study, but possibly affectingobserved behavior.



Two uses

“Experimenter makes things happen when he/she

wants them to happen” (Johnson and Solso,

1984) Arrangement of conditions so that the

experimenter can attribute result of experiment to independent variable and not

any other variable. (Johnson and Solso, 1984)



Means for ruling out threats to validity.

Provides a standard against which to

compare the effect of a particular IV.

(McBurney)



No!

Control without control group, wherein two

experimental groups are given differing

treatment and the effects subsequently

compared:

Group Treatment

1 A1

2 A2



Do students learn better with audio or video?

Group of students is divided.

Group 1 is taught using audio alone.

Group 2 receives instruction via video.

Group Treatment

Audio A1

Video A2



No!

Experiment may instead be given a control

condition, wherein different subjects each

experience a condition and thereby serves as its

own control

(All Subjects) Condition Treatment

Experimental Condition Present

Control Condition Absent



The shampoo test

A group of participants is asked to test a type of

conditioner with one type of shampoo. Effects

are observed and rated.

The same group is asked to use only shampoo.

Effects are observed and rated.

Comparison between effects.

(All Subjects) Condition TreatmentWith conditioner Present

Shampoo only Absent



1. Laboratory Setting

Scientific laboratory: place set up to allow the

mot appropriate control over variables of

interest in the research

Has all the items/equipment required

MAXIMUM CONTROL!

NEED NOT

BE STERILE!



2. Research setting as preparation

Skinner Box

(B.F. Skinner)

Device used to

study learning in

small animals.

Unlike other

implements such

as mazes, it

ensures that only

response time is

being studied and

not number of

turns or speed,which are possible

confounding

variables.



3. Instrumenting response

Improving measurement of behavior under

study

Setting up standardized benchmarks for

comparison, easy reference

Use of measuring devices as instruments for

reducing behavior to numbers or to other forms

convenient to data analysis.

e.g. Taylor Manifest Anxiety Scale



branch of measurement that involves the

construction of an instrument that associatesqualitative constructs with quantitativemetric units



Observing and recording of observations

collected as part of a research effort

(Nation, 1997)

Assignment of numbers to thingsQuantifying



4 levels:

Nominal

Ordinal

Interval Ratio

Depending on suitability, none is better than

another



Basic scale of measurement

Numbers or symbols representing

differences between objects or persons

Process of grouping into classesNo qualitative features



Uses numbers to order objects from a

continuum of high to low

Provides information about rank

Distances between values may be unequal



Assigns a number to an object or person such

that the number of units of measurement isequal to the amount of attribute possessed(to scale!)

Identifiable levels

No absolute zero point as consistent

reference.

Reflected values on scale not proportional tocharacteristics

Includes all measurements of ordinal and

interval levels.



Intervals between numbers are equal, but

zero point is arbitrary

e.g. Temperature



Ex. 32oF

The interval between 32oF and 33oF is the

same as the interval between 85oF and 86oF

0o

F does NOT imply absence of temperature! 0oF and 0oC are not equal.



Most sophisticated form of measurement

Zero point present!

Indicates absence of attribute measured

Proportional relationships represent actualamounts of the characteristic being

measured.



Type of Scale Measurement Scale Characteristics of Scale

Statistical Possibilities

Non-interval Nominal Names or designations of discrete

units/categories.

1. Mode

2. Percentage

3. Chi-square

Non-interval Ordinal Values such as “more

or less,” but w/o

specifying size of intervals

1. Mode

2. Percentage

3. Chi-square4. Median

5. Percentile rank

6. Rank correlation

Interval Interval Equal intervals or

degree of difference,

zero point arbitrary

1. Mean

2. Standard deviation

3. T-Test

4. F-Test

5. Product-Moment

Correlation

Interval Ratio Equal intervals,

absolute zero point

1. Geometric mean

2. Harmonic mean

3. Percent variation



Maleske, T.M. (1995). Foundations fro

Gathering and Interpreting Behavioral Data:

An Introduction to Statistics. Pacific Grove,

California: Brooks/Cole Publishing Co.

Shardson, R.J. (1988). Design of Research in

the Behavioral Sciences. In Statistical

Reasoning for the Behavioral Sciences (pp.

15-23). Massachussets: Allyn & Bacon, Inc. Blalock, H.M. Jr. (1981). Social Statistics.

McGraw Hill, Inc.



Johnson, H.H., Solso, R.L. (1984). An

Introduction to Experimental Design in

Psychology: A Case Approach. New York, N.Y.

Harper and Row Publications, Inc.

Kontowitz, B.H., Roediger, R.L., Elmes, D.G.

(1988). Experimental Psychology. St. Paul,

MN: West Pub. Co.

Christensen, L.B. (1997). The IndependentVariable. In Experimental Methodology (pp.

195-199). Needham Heights, MA: Allyn &

Bacon, Inc.



Johnson, H.H., Solso, R.L. (1984). An

Introduction to Experimental Design in

Psychology: A Case Approach. New York, N.Y.

Harper and Row Publications, Inc.

Kontowitz, B.H., Roediger, R.L., Elmes, D.G.

(1988). Experimental Psychology. St. Paul,

MN: West Pub. Co.

Christensen, L.B. (1997). The IndependentVariable. In Experimental Methodology (pp.

195-199). Needham Heights, MA: Allyn &

Bacon, Inc.



Nation, J.R. (1997). Research Methods.

Upper Saddle River, NJ. Prentice Hall, Inc.

McBurney (1998). Research Methods.



Variables in Your Science Fair Project.

http://www.sciencebuddies.org/science-fair-

projects/project_variables.shtml

Trochim, William M.K. (2006) ResearchMethods Knowledge Base. Article on Variables

Retrieved from

http://www.socialresearchmethods.net/kb/v

ariable.php

http://www.experiment-

resources.com/research-variables.html

http://www.sciencebuddies.org/science-fair-projects/project_variables.shtml


http://www.socialresearchmethods.net/kb/variable.php


http://www.experiment-resources.com/research-variables.html














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Variables and Scales