Basic Terms and Definitions

Question 1

Descriptive statistics

Answer 1

summarize, understand, and describe a group of numbers from a research study

Question 2

What are examples of descriptive stats

Answer 2

1. measure of central tendency (mean, median, mode)

2. variability (range, varience, sd)

Question 3

Inferential statistics

Answer 3

1. draw conclusions and make inferences based on numbers from a research study, but go beyond these numbers
2. if there is a difference between groups
3. how sure we are about our conclusions

Question 4

Variable

Answer 4

condition or characteristic that can have different (varying) values (ex. male/female, …22,23,24…,

Question 5

Score

Answer 5

the value of a particular person’s answer (ex. male, 25yrs old, 15 sexual partners)

Question 6

Variability

Answer 6

how much change there is in a group of scores

Question 7

Variance

Answer 7

a specific measure of variability

Question 8

Correlational Research Designs

Answer 8

examines if there is a relationship between variables

• “what does knowledge of x tell us about y”
• naturally occurring variables

Question 9

Experimental Research Designs

Answer 9

goal is to determine why something happens

• “what causes X?”
• control and manipulation of variables

Question 10

Independent variable

Answer 10

variable that the researcher manipulates/changes

Question 11

Dependent variable

Answer 11

variable that changes because of IV

Question 12

Components of an experiment

Answer 12

1. Must have more than one level of IV
2. several, stable/reliable DVs
3. control variables
4. random assignment

Question 13

Control variables

Answer 13

keeping everything else constant

Question 14

Random assignment

Answer 14

purpose of random assignment is to create equivalent groups

Question 15

Population

Answer 15

set of all cases of interest, generally a theoretical concept (not always measurable)

Question 16

Sample

Answer 16

subset of population that is being studied; something to be concerned about is biased samples

Question 17

Biased Samples

Answer 17

sample that systematically underselects or overselects from certain groups in the population

Question 18

Parameter

Answer 18

Some characteristic of population

Question 19

Statistic

Answer 19

some characteristic of sample

Question 20

Scales of measurement

Answer 20

1. Nominal
2. Ordinal
3. Interval
4. Ratio

Question 21

Nominal

Answer 21

mutually exclusive categories (yes or no)

Question 22

Ordinal

Answer 22

placing variables in a “ranked” order (no, somewhat, yes)

Question 23

Interval

Answer 23

equal distances between points on the scale (temp., on scale from 1-10 how helpful)

Question 24

Ratio

Answer 24

exactly like interval scale, but has a true zero (#oof cigs smoked today)

Question 25

IV measurement

Answer 25

often at a nominal level

Question 26

DV measurement

Answer 26

Data analysis is limited when using nominal or ordinal data

- interval data is desirable

Question 27

Unimodal data

Answer 27

only one very high area (mode)

Question 28

Bimodal data

Answer 28

two very high areas

Question 29

Multimodal data

Answer 29

many very high areas

Question 30

Rectangular data

Answer 30

all values have about the same frequency

Question 31

Symmetrical data

Answer 31

many psychological variables (height, weight, attitudes, work productivity); distribution looks the same on both sides if you split it down the middle

Question 32

Skewed data

Answer 32

majority of responses are at low or high ends of the scale

Question 33

Central tendency

Answer 33

a measure that refers to the typical score in a distribution

- “center of data,” “best representation”

Question 34

Measures of central tendency

Answer 34

mean, median, mode

Question 35

mean

Answer 35

average - interval/ratio data

Question 36

median

Answer 36

middle score - ordinal data (very skewed interval/ratio data)

Question 37

mode

Answer 37

most frequent - nominal data - bimodal distribution

Question 38

Properties of the mean

Answer 38

1. the value is the value around which all observed values are balanced
2. the point at which the sum of the squared deviations is minimized
3. influenced by extreme values (main disadvantage)

Question 39

Variability

Answer 39

the spread of scores in a distribution

Question 40

Types of variability

Answer 40

range, variance, standard deviation

Question 41

Range

Answer 41

the distance between the larges and smallest scores (only reflects two most extreme scores

Question 42

Variance

Answer 42

the sum of the squared deviations from the mean, divided by N-1

Question 43

Steps for calculating the varience

Answer 43

1. subtract the mean from each of the scores to get deviations
2. square each deviation
3. add all squared deviations
4. divide by the total number of scores minus 1

Question 44

Standard deviation

Answer 44

the most widely used measure of variability (square root of variance)