Exploring Univariate Data Vocab 1B

median

midpoint of a distribution

mean

the average of all the individual data values

statistic

a number that describes some characteristic of a sample

parameter

a number that describes some characteristic of a population

resistant

a statistical measure that is not affected much by extreme data values

range

the distance between the minimum value and the maximum value

Standard Deviation

measurers the typical distance of the values in a distribution from the mean.

S_x

Symbol for standard deviation

Quartiles

divide an ordered data set into four groups having roughly the same number of values

first quartile

the median of the data values that are to the left of the median

Q₁

symbol for first quartile

third quartile

The median of the data values that are to the right of the median in the ordered list

Q₃

Symbol for 3rd Quartile

interquartile range

Distance between the first and third quartiles of distribution

IQR

Symbol for Interquartile range

the 1.5 x IQR Rule

Identifies outliers if something falls more or less than 1.5 x IQR

Five-number summary

consists of the minimum, the first quartile, the median, the third quartile, and the maximum

boxplot

visual representation of the five number summary

pth percentile

The value with p% of observations less than or equal to it

standardized value

Tells us how many standard deviations from the mean the value, and in what direction.

z-score

Shorthand for standardized score

cumulative relative frequency graph

Plots a point corresponding to the percentile of a given value in a distribution of quantitative data. Consecutive points are then connected with a line segment to form the graph

Normal distribution

described by a symmetric, single-peaked, mound shaped curve called a normal curve. It is completely specific by two parameters: Its mean u and standard deviation O

Normal curve

a symmetric, single peaked, mouth-shaped curve that describes normal distribution.

Empirical Rule

In a normal distribution with mean U and standard deviation O, it stated that:

• about 68% of the values fall within 1O of the mean U

• About 95% of the values fall within 2O of the mean U

• about 99.7% of the values fall within 3Q of the mean U

U

U

O

o

Standard Normal Distribution

the normal distribution with mean 0 and standard deviation 1