Graphs
A bar graph that shows the frequency of data
within equal intervals.
Histogram
What is the arithmetic average of a distribution,
obtained by adding the scores and then
dividing by the number of scores?
Mean
A sample in which every element in the
sample has an equal chance of being selected.
Random Sample
Data identified by something other than
numbers.
Qualitative
An experiment that observes individuals
and measures variables of interest but does
not attempt to influence the responses.
Observational Study
IQR
Range of the middle 50% of the values; Q3-
Qi 75th percentile - 25th percentile.
The middle score in a distribution; half the
scores are above it and half are below it.
Median
The entire aggregation of items from which
samples can be drawn.
population
quantitative
Data or datum being numerically defined.
Placebo effect
Experimental results caused by expectations
alone; any effect on behavior caused by the
administration of an inert substance or
condition, which is assumed to be an active
agent.
Graphs a dot for each case against a single
axis.
Dot plot
mode
The datum which occurs the most in a set of
data.
Probability
The likelihood that a particular event will
occur.
Items selected at random from a population
and used to test hypotheses about the
population.
sample
What is the mean?
2,3,2,4,5,2,3,5,6
3.5
Steamplot
A graphical representation of a quantitative data set. Leading values of each data point are presented as stems and
second digits are given as leaves.
Z score
A parametric inferential statistical test of the null hypothesis for a single sample where the population standard deviation is known.
Quota sample
A sample deliberately constructed to reflect
several of the major characteristics of a given
population.
Sample Space
All possible outcomes of an experiment
Bias introduced to a sample when individuals can choose on their own whether to participate in the sample.
Voluntary response bias
Scatterplot
A graphed cluster of dots, each of which
represents the values of two variables.
An extreme deviation from the mean.
outlier
Response bias
Anything in the survey design that influences
the responses from the sample.
Sampling Distribution
The distribution of values taken by the
statistic in all possible samples of the same
size from the same population.
Emperical rule
States that, in a normal distribution, about
68% of the terms are within one standard
deviation of the mean, about 95% are within
two standard deviations, and about 99.7%
are within three standard deviations (normal
curve).