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Stat Vocab Chapter 1
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Terms in this set (42)
Association
occurs between two variables if specific values of one variable tend to occur in common with specific values of the other
back-to-back stemplot
used to compare the distribution of a quantitative variable of two groups.
bar graph
used to display the distribution of a categorical variable or to compare the sizes of different quantities. The horizontal axis of the bar graph identifies the categories or quantities being compared.
bimodal
describes a graph of quantitative data with two clear peaks
boxplot
a graph of the five-number summary. The box spans the quartiles and shows the spread of the central half of the distribution. the median is marked within the box. lines extend from the box to the extremes and show the full spread of the data
categorical variable
places an individual into one of several groups or categories
conditional distribution
describes the values of one variable among individuals who have specific value of another variable. there is a separate conditional distribution for each value of another variable. there is a separate conditional distribution for each value of the other variable
data analysis
a process of describing data using graphs and numerical summaries
dotplot
a simple graph that shows each data value as a dot above its location on a number line
distribution
tells what values a variable takes and how often it takes these values
first quartile
if the observations in a data set are ordered from lowest to highest, the first quartile is the median of the observations whose position is to the left of the median
the five-number summary
consists of the smallest observation, the first quartile, the median, the third quartile, and the largest observation, written in order from smallest to largest
frequency table
displays the count (frequency) of the observations in each category or class
histogram
displays the distribution of a quantitative variable.
individuals
objects described by a set of data. individuals may be people, animals, or things
interquartile range
IQR = Q(3) - Q(1)
marginal distribution
the distribution of values of that variable among all individuals described by the table
mean
the arithmetic average. to find the mean of a set of values, add their values and divide by the number of observations
median m
the midpoint of a distribution, the number such that half of the observations are smaller and the other half are larger
mode
the value or class in a statistical distribution having the greatest frequency
multimodal
describes a graph of quantitative data with more than two clear peaks
outlier
an individual value that falls outside the overall pattern of a distribution
overall pattern
shape, center, and spread describe the overall pattern of the distribution of a quantitative variable
pie chart
shows the distribution of a categorical variable as a "pie" whose slices are sized by counts or percents for the categories
quantitative variable
takes the numerical values for which it makes sense to find an average
range
the range of a set of quantitative data is the maximum value minus the minimum value
relative frequency table
shows the percents (relative frequencies) of observations in each category or class
resistant measure
a statistic that is not affected very much by extreme observations
roundoff error
the difference between the calculated approximation of a number and its exact mathematical value
segmented bar graph
used to compare the distribution of a categorical variable in each of several groups
side by side bar graph
used to compare the distribution of a categorical variable in each of several groups
simpsons paradox
an association between two variables that holds for each individual value of a third variable can be changed or even reversed when the data for all values of the third variable are combined
skewness
a distribution is skewed to the right if the right side of the graph is much longer than the left side. it is skewed to the left if the left side of the graph is much longer than the right side
splitting stems
a method for spreading out a stemplot that has too few stems
standard deviation s(x)
measures the average distance of the observations from their mean (calculated with formula s(x)=.....
stemplot
a simple graphical display for fairly small data sets that gives a quick picture of the shape of a distribution while including the actual numerical values in the graph
symmetry
if the right and left sides of a graph are approximately mirror images of each other
third quartile q(3)
the median of the part of the data which is greater than the median; also the 75 percentile
two-way table
organizes data about two categorical variables
unimodal
describes a graph of quantitative data with a single peak
variables
an characteristic of an individual
variance
the average squared distance of the observations in a data set from their mean
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