Psychological Measurement Chapter 4

Question 1

Level of measurement

Answer 1

relationship among the numbers we have assigned to the information

Question 2

Nominal

Answer 2

Assign numbers to objects where different numbers indicate different objects

Female = 1, Male = 2

Question 3

Ordinal

Answer 3

Assign numbers to objects, numbers also have meaningful order

1st place, 2nd place, 3rd place

Question 4

Interval

Answer 4

Numbers have order but there are also equal intervals between adjacent categories

the difference between 78 degrees and 79 degrees (1 degree) is the same as 45 and 46 degrees (1 degree)

Question 5

Ratio

Answer 5

Differences are meaningful (like interval), plus ratios are meaningful and there is a true zero point

10 pounds is twice as much as 5 pounds (ratios are meaningful: 10/5= 2)
- Zero pounds means no weight or an absence of weight (true zero point)

Question 6

Raw scores

Answer 6

basic scores calculated form a psychological test

• We convert raw scores into more informative standards scores

Question 7

Frequency distribution

Answer 7

an orderly arrangement of a group of numbers

Question 8

Histogram

Answer 8

a bar graph used to represent frequency data in statistics

Question 9

normal distribution

Answer 9

(Carl Frederich Gauss)

Perfect and symmetrical
- Forms a bell shaped curve

Question 10

Measures of central tendency

Answer 10

value that helps us understand the middle of a distribution or set of scores (Mean, median and mode)

Question 11

Mode

Answer 11

Refers to the data value that is most frequently observed

Question 12

Median

Answer 12

Refers to the data value that is positioned in the middle of an ordered data set
- Smallest to largest order

Question 13

Mean

Answer 13

Average between all data points

Question 14

Range

Answer 14

Max - Minimum (how much room distribution takes)

Question 15

Standard deviation

Answer 15

How close the values in a data set are to the mean

+2 indicates that scores vary around the mean by 2 points

Question 16

Variance

Answer 16

The degree of spread within the distribution

sum of the squared differences from the mean of each score, divided by the number of scores

Question 17

Correlation coefficient

Answer 17

is a statistic that we typically use to describe the relationship between two or more distributions of scores

Question 18

Pearson Product-Moment Correlation Coefficient

Answer 18

When variables are on an interval or ratio scale

Question 19

Spearman Rank Correlation Coefficient

Answer 19

When the variables are on an ordinal scale

Question 20

Standards scores

Answer 20

Units we transform test scores into (From raw scores)

Question 21

Linear transformations

Answer 21

change the unit of measurement but do not change the characteristics of the raw data

Question 22

Area transformations

Answer 22

change not only the unit of measurement but also the unit of inference

Question 23

Percentage

Answer 23

divide a raw score by the total possible scores and hen multiply answer by 100

Question 24

Standard deviation unit

Answer 24

How many standards deviations an individual score falls away from the mean

Question 25

Z-score

Answer 25

ells how many standard deviations someone is above or below the mean.

-Similar to standard deviation except it is represented as a whole number with a decimal point

Question 26

T-Score

Answer 26

(or standardized scores) are a conversion (transformation) of raw individual scores into a standard form, where the conversion is made without knowledge of the population’s mean and standard deviation.

• Similar to standard deviation, help us understand how many standard deviations an individual test score is above or below the distribution mean.