Exam 1 (Ch. 1 & 2) Flashcards
Descriptive statistics
calculation that produces a number that summarizes or describes a set of data
Inferential statistics
calculations based upon measurements from a sample used to reach a conclusion about a larger unmeasured population
Population
all scores of the individuals of interest for investigation; defined by the investigator
Sample
scores of a subset of the population; defined by the investigator
Parameter
numerical (number) or nominal (categorical) characteristic of a population; constant and usually becomes a variable of interest for research questions
Statistic
a numerical or nominal characteristic of a sample; used as an estimate of the population parameter; differs between samples and is variable (changeable)
Variable
Any measurable characteristic that varies from one situation to the next
(Raw) score
Measurement of a variable
Quantitative
amount or degree of the variable; numeric and continuous
Interval
intervals between numbers are equal
Ratio
has a true zero point
Qualitative
categorical characteristic; not continuous or numeric
Nominal
reflects membership in groups
Ordinal
includes greater or less than relationships
Order of Variables
Nominal -> Ordinal -> Interval -> Ratio
Experimental
variables are manipulated and their effects on other variables are measured (relationship between)
Independent variable (IV)
manipulated
Dependent variable (DV)
measured
Control group
placebo/fake treatment; for comparison
Extraneous variable
uncontrolled/uneliminated variable that can affect outcome
Confounding variable
extraneous variable that mirrors IV outcome, making it difficult to determine relationship between IV and DV (frequently seen in human subjects)
Raw scores
raw data collected through research; unedited
Simple frequency distribution
ordered arrangement of scores that shows frequency
Grouped frequency distribution
ordered arrangement of scores condensed into meaningful groups
Class intervals
data grouped into equal-sized ranges
Abscissa
horizontal axis (X)
Ordinate
vertical axis (Y)
Frequency polygon
quantitative; intersecting points of axes
Histogram
quantitative; similar to bar graph but represents distribution of scores (discrete data/whole numbers); no gaps between bars
Bar graph
categories of a qualitative variable; spaces between bars
Line graph
relationship between two variables (X & Y); aka scatterplot
Bell-shaped
most frequent scores fall around the mean (average); aka normal distribution/normal curve
Positive/Right Skewed
frequency scores are low (tail points right)
Negative/Left Skewed
frequency scores are high (tail points left)
Rectangular
uniform distribution (X values have same frequency)
Bimodal
2 humps
