Statistics

Question 0

What are the characteristics of an interval variable?

Answer 0

it has order and equal spacing (intervals) between items

eg. temperature

Question 1

What is statistics?

Answer 1

the process of representing or analyzing numerical data

Question 2

What are the characteristics of a ratio variable?

Answer 2

order, equal intervals, and a real zero

eg age

Question 3

What is the name for a graph with plotted points connected by lines?

Answer 3

a frequency polygon

Question 4

What category do the mean, median, and mode belong to?

Answer 4

measures of central tendency

Question 5

What is another term for the range of data?

Answer 5

the spread of the data

Question 6

How is the standard deviation calculated?

Answer 6

• subtract each value from the mean
• square each of these (to remove negatives)
• add up the sum of the squared values
• divide the sum of squares by number of values (n)
• take the square root

Question 7

How are the variance and standard deviation related to each other?

Answer 7

the STDEV is the square root of the variance

Question 8

What is a unimodal distribution?

Answer 8

a distribution with only one peak

Question 9

What is a z-score?

Answer 9

a representation of how many STDEVs a value is from the mean

Question 10

In a standard normal distribution, what are the mean and standard deviation?

Answer 10

mean = 0

standard dev = 1

Question 11

What percentage of a population will fall within 1 standard deviation of the mean in a normal distribution?

Answer 11

34.13% above + 34.13% below = 68.26%

Question 12

What percentage of a population will fall within 2 standard deviations of the mean in a normal distribution?

Answer 12

95.44%

Question 13

What is a bimodal distribution?

Answer 13

a distribution with two peaks, with a valley in between

Question 14

What is the characteristic of a negatively skewed distribution?

Answer 14

the low tail trails off for a long time, with the peak pushed to the right/positive end

Question 15

What is the characteristic of a positively skewed distribution?

Answer 15

the high tail trails off for a long time, with the peak pushed to the left/low end

Question 16

What is an example curvilinear correlation?

Answer 16

arousal and performance, which has a inverted U relationship

Question 17

When can the Spearman r correlation coefficient be used?

Answer 17

when the values are ranked/ordinal values

Question 18

What are the minimum and maximum values of a Pearson’s r correlation?

Answer 18

-1 and +1

Question 19

How do the terms statistics and parameters relate to each other?

Answer 19

statistics refer to numbers that describe a sample
parameters refer to numbers that describe populations

statistics are used to estimate parameters

Question 20

What is a Type I error?

Answer 20

the 1 in 20 error that you found sig results when in fact it was such random sampling variation

Question 21

What is a Type II error?

Answer 21

not finding sig (for example, sample too small) even though there is a real difference between groups

Question 22

What can a Chi-square test tell us about two groups?

Answer 22

whether the two groups differ in size or proportions

Question 23

What are linear regressions used for?

Answer 23

going from correlation coefficients to predictions

eg can now predict dependent variable from score on independent variable

Question 24

What is the line of best fit in a regression analysis called?

Answer 24

a least-squares line

or the regression line

Question 25

What do criterion-defined tests measure?

Answer 25

mastery of a particular skill or subject matter

Question 26

What do domain-referenced tests measure?

Answer 26

less well-defined properties like intelligence or personality tests

Question 27

What two features do domain-referenced tests need?

Answer 27

reliability

validity

Question 28

What does reliability of a test measure?

Answer 28

how stable responses to the test or scale are

Question 29

What are the two types of test reliability?

Answer 29

test-retest reliability

split-half reliability

Question 30

What does examining split-half reliability of a test reveal about it?

Answer 30

its internal consistancy

Question 31

What is an item analysis of a test?

Answer 31

analyzing how a large group of people responded on one item

the goal is to reveal questions that don’t discriminate well so they can be removed

Question 32

What does validity of a test measure?

Answer 32

how well the test actually measures a construct

Question 33

What are the two main types of validity?

Answer 33

internal and external

Question 34

What are the four main aspects of external validity?

Answer 34

• concurrent validity
• construct validity
• content validity
• face validity

Question 35

What process measures concurrent validity?

Answer 35

cross-validation of test results

Question 36

What is concurrent validity?

Answer 36

whether a responses on new test/scale correlate with other measures known to test the same construct

Question 37

What is construct validity?

Answer 37

whether the test actually assesses the abstract concept being measured

Question 38

What is content validity?

Answer 38

whether the content of the test covers the broad spectrum of content of the construct being measured, not just a part of it

Question 39

What is face validity?

Answer 39

whether at face value the items of a test appear to test the targeted construct

Question 40

What technique did Donal Campbell and Donald Fisk contribute to psychological research?

Answer 40

the multitrait-multimethod technique to determine the validity of psychometric tests