STATISTICS

Σ2X²

1.Perform any operation within parentheses. 2.Perform any exponentiation (such as squaring). 3.Perform any multiplication or division. 4.Perform any summations (Σ). 5.Complete any additional addition or subtraction in left to right order.

statistic

A characteristic, usually a numerical value, which describes a sample

The participants in a research study self-report their sleep quality levels by choosing the response option that best characterizes their average sleep quality per night from the following response options: 1 = extremely low sleep quality, 2 = very low sleep quality, 3 = low sleep quality, 4 = extremely high sleep quality. Which measurement scale is being used to classify sleep quality? A. Ratio B. Ordinal C. Interval D. Nominal

B. Ordinal

The mathematical expression of ΣX - 2 differs from the mathematical expression of Σ(X - 2) in each of the following ways except for which?

Squaring takes place in one equation but not the other.

Multimodal

a distribution with more than two scores with greatest frequency

A researcher surveys a sample of n = 10 adults and asks them to indicate their favorite day of the week. If the data were organized in a frequency distribution table, what would be included in the first column?

a list of days of the week

central tendency

a statistical measure to determine a single score that defines the center/midpoint of a distribution

Keith conducts a research study to examine how mental fatigue influences frustration levels. He has one group of participants complete a mentally exhausting problem-solving task for ten minutes, and a second group of participants complete an easy crossword puzzle for ten minutes. Then, he observes participant reactions to being prevented from achieving a desired goal on a second unrelated task as a measure of frustration levels. In this research study, the experimental condition is _____. a. frustration levels. b. task type. c. the group of participants who complete the mentally exhausting problem-solving task. d. the group of participants who complete the easy crossword puzzle.

c. the group of participants who complete the mentally exhausting problem-solving task.

standardized distribution

composition of data used to make dissimilar distributions comparable

Which kind of variable requires the use of real limits?

continuous

line graph

diagram used when values on horizontal axis are measured on an interval or ratio scale

Bimodal

distribution with two scores with greatest frequency

X=μ+zσ

equation used to transform z-scores back into X values, for a population

X=M+zs

equation used to transform z-scores back into X values, for a sample

Sarah is conducting a research study in which one group of participants consume one cup of coffee, whereas another group of participants consume two cups of coffee. Then, she assesses attention levels of these participants following coffee consumption. This is an example of a(n) _____ research study.

experimental

weighted mean

formula combining multiple sets of scores and dividing to find overall mean for combined group

z=(x-μ)/σ

formula used to transform X values into z-scores, for a population

z=X-M/S

formula used to transform X values into z-scores, for a sample

population mean

formula wherein all scores in the population are added, and then divided by N

sample mean

formula with symbols to signify population subset values

control condition

group that either receives no treatment or receives a neutral, placebo treatment.

experimental condition

group that receives the experimental treatment.

Which type(s) of frequency distribution graph(s) should be used for data that come from an interval scale of measurement?

histograms or polygons

If a set of scores is displayed using a smooth curve, which scale of measurement was used to measure the scores?

interval or ratio

experimental method

manipulating one variable while another variable is observed and measured.

descriptive research

measuring separate variables with the intent of simply describing the individual variables

pre-post study

method of using the passage of time to create the groups of scores.

Median

midpoint in a list of scores listed in order from smallest to largest

correlational method

observing two different variables to determine whether there is a relationship between them.

Barbara is a psychologist who measures relationship satisfaction among couples by observing non-verbal behavior (e.g., smiling, mimicking partner actions). In this example, non-verbal behavior is an example of a(n) _____.

operational definition.

raw score

original, unchanged scores that are the direct result of measurement

σ^2

population variance

nonequivalent groups study

score comparison method where the researcher does not control which participants go into which group.

Mode

score or category that has the greatest frequency in a frequency distribution

z-score transformation

relabeling of X values in a population into precise X-value locations within a distribution

standardized score

result from relabeling data into new table with positive, whole-number predetermined mean and standard deviation

sample standard deviation

s=√(s^2 )

s^2

sample variance

nominal scale

set of categories that have different names.

interval scale

set of ordered categories that are all intervals of exactly the same size.

ratio scale

set of ordered categories wherein a zero score indicates none of the variable being measured.

minor mode

shorter peak when two scores with greatest frequency have unequal frequencies

z-score

specifies the precise location of each X value within a distribution

σ

standard deviation

mean

sum of the scores divided by the number of scores

sample variance

s²= SS/n-1

grouped frequency distribution table

table presenting groups of scores rather than individual values

major mode

taller peak when two scores with greatest frequency have unequal frequencies

independent variable

value that is manipulated by the researcher.

dependent variable

value that is observed to assess the effect of the treatment. measuring separate variables with the intent of simply describing the individual variables.

quasi-independent variable

value that is used to create the different groups of scores.

Under which circumstance is a score that is 15 points above the mean an extreme score relatively far from the mean?

when the population standard deviation is much smaller than 15

population standard deviation

σ= √σ^2

population variance

σ² = SS/N