Chapter 5: Variables

Question 1

aspect of a testing condition that can change or take on different characteristics with different conditions

Answer 1

variable

Question 2

How are variables related to theoretical concepts?

Answer 2

• The variables are tangible: duration, frequency, rate, or intensity of bar presses; items checked on a questionnaire; murders committed; books written.
• The theoretical concept is intangible: hunger, love, motivation, anxiety.
• The variables are related to the theoretical concepts by means of the operational definitions used to measure the concepts.

Question 3

dependent variable:

Answer 3

a measure of the subject’s behavior that reflects the independent variable’s effects

Question 4

independent variable:

Answer 4

the condition manipulated or selected by the experimenter to determine its effect on behavior

Question 5

What are the levels of an independent variable?

Answer 5

Levels: Every independent variable has at least two values; otherwise, it wouldn’t be a variable. These values are commonly called levels.

• Frustration or no frustration are the minimum 2 levels

Question 6

variable of interest:

Answer 6

a variable for which its role in the cause and effect of an observed relationship is not clear

• Does watching violent tav cause aggression or does having a violent tendency predispose you to watching violent tv?

Question 7

subject variable:

Answer 7

a difference between subjects that cannot be controlled but can only be selected

For e.g.:

• Poverty
• Age
• IQ
• gender

Question 8

confounded variable:

Answer 8

one whose effect cannot be separated from the supposed independent variable

• For e.g.:
• Lack of exercise (IV) = weight gain (DV)
• You test men at 16 and women at middle age only
• Age is a confounding variable that has an effect on the results

Question 9

Distinguish between quantitative and categorical variables. Give examples.

Answer 9

A quantitative variable is one that varies in amount - you can measure it, whereas a categorical variable varies in kind.

• Examples of quantitative variables would be weight, height, age
• College major and gender, marital status, political affiliation would be categorical variables: non-numeric though you can assign like a nominal scale

Question 10

What is the difference between continuous and discrete variables?

Answer 10

If you wanted to get to the top of a mountain: trail or gondola:

gondola stops at 3 places - bottom, middle and top so it’s a discreet variable.

Trail is continuous

continuous variable: one that falls along a continuum and is not limited to a certain number of values - you can measure on a continuum - weight, height

discrete variable: one that falls into separate bins with no intermediate values possible

• I have 2 siblings I cannot have 2.6 siblings
• it is counted and not measured

Question 11

real limits:

Answer 11

rounding down or up at the .5 mark

the interval defined by the number plus or minus half the distance to the next number

Question 12

apparent limits:

Answer 12

the point indicated by a number

Question 13

4 types of measurement with description

Answer 13

Question 14

Is a person with an IQ of 120 “twice as smart” as a person with an IQ of 60? Why, or why not?

Answer 14

No because it is an interval scale and not a ratio scale

Question 15

0reliability:

Answer 15

consistency of a measurement that gives the same result on different occasions

Question 16

validity:

Answer 16

(of a measurement) the property of a measurement that tests what it is supposed to test

Question 17

construct validity (of a test):

Answer 17

• First, the test should actually measure whatever theoretical construct it supposedly tests, and not something else
• A test of leadership ability should not actually test extraversion
• • Second, it should measure what it intends to measure but not measure theoretically unrelated constructs
• A test of musical aptitude should not require too much reading ability, for example.
• Third, a test should prove useful in predicting results related to the theoretical concept it is measuring.
• A test of musical ability should predict who will benefit from taking music lessons

Question 18

Face validity

Answer 18

is the idea that a test should appear to any person to be a test of what it is supposed to test

• more a problem of public relations than of true validity

Question 19

Content validity

Answer 19

test should sample the range of the behavior that is represented by the theoretical concept being measured

• An intelligence test that measured only spatial ability would not have sufficient content validity

Question 20

Criterion validity

Answer 20

a valid test should relate closely to other measures of the same theoretical construct

• A valid test of intelligence should correlate highly with other intelligence tests.

Question 21

If the criterion of an intelligence test is how well the test can predict some future performance of the child, such as graduation from college, then it is called –

Answer 21

predictive validity

Question 22

If the criterion of an intelligence test is whether it correlates with how well a child is doing in school at the time the test is given, it is called —

Answer 22

concurrent validity

Question 23

Using a bathroom scale as an example, explain why a measurement can be reliable and yet invalid.

Answer 23

• random error may be caused by exactly where I place my feet on the scales, how I lean, whether I just had a drink of water, and so forth. But if we don’t measure these other independent variables, we can lump them all into random error.

Question 24

I find, however, that I weigh less in the morning, wearing my night clothes, and if I stand on a certain spot on the scales. But this isn’t necessarily my true weight because now I have introduced —

Answer 24

systematic error

Question 25

• — is never desirable in research, but it may not be such a serious problem if the error is the same for the entire study—that is, all groups or conditions of the study are equally affected by the — .
• — is always a serious problem in research because it can reduce the precision

Answer 25

systematic error, random error

Question 26

test-retest reliability:

Answer 26

the degree to which the same test score would be obtained on another occasion

Question 27

internal consistency:

Answer 27

the degree to which the various items on a test are measures of the same thing

Question 28

— is determined when the items on a test are divided into two sets as if they were two separate tests

Answer 28

Split-half reliability