Unit 1 Stats Vocab

A measurement that is relatively unaffected by extreme observations

resistant value

Individual observations that are quantitative in nature

numerical data

The proportion or percent of observations within a category. It is found by dividing the frequency of a category by the sum of the frequencies

relative frequency

The average value in an entire population denoted by µ      

population mean

Extreme observations in the data set

outliers

A measurement that describes the spread of middle 50% of a data set

IQR

A distribution that resembles a mirror image on either side of the center

symmetrical distribution

A measurement that describes variability - the average of the squared deviations from the mean.                    

s²= Σ ( x_i- x )²/ ( n – 1)

variance

The middle value in an ordered list of sample observations.  It is insensitive to outliers

median

A graph used with a univariate numerical data set where frequencies are shown on the vertical axis, and intervals or bins define the values on the horizontal axis

histogram

A descriptive measure of a population

parameter

Qualitative variables allowing for classification of individuals based on some attribute or characteristic

categorical data

A graphical display used with categorical data, where frequencies for each category are shown in vertical bars

bar chart

The minimum, the first quartile Q₁ , median, third quartile (Q₃), and maximum values in a data set.

five number summary

A descriptive measure of a sample

statistic

A graphical display of the five-number summary of a set of data, which also shows outliers

boxplot

The row totals and column totals in a two-way table of the two individual variables

marginal distribution

A unimodal, asymmetric, distribution that tends to slant – most of the data are clustered on one side of the distribution and “tails” off on the other side

skewed distribution

A measure of variability that is the average distance of the observation from the mean (the square root of the variance)

standard deviation

A distribution with two clear peaks

bimodal

The distributions of the row variable for each value of the column variable and the distribution of the column variable for each value of the row variable

conditional distribution

In a numerical data set, describes how widely dispersed the values are from the mean and each other

variability

All data values in the distribution have the same or close to same frequencies

uniform distribution

A measurement of variability that is found by finding the difference between the maximum and minimum values of a data set.

range

The difference between an observation and the mean of the data set

deviation from the mean