Stats Key Terms 2

STA2023 Week 2 key terms

Mean

Mean

The average of a data set: (x1 + x2 …+ Xn)/n

Median

the middle value of a set of numbers

Mode

the most frequently occurring number found in a set of numbers.

Five number summary

• The minimum.

• Q1 (the first quartile, or the 25% mark).

• The median.

• Q3 (the third quartile, or the 75% mark).

• The maximum.

First quartile

the value under which 25% of data points are found when they are arranged in increasing order

Third quartile

the value under which 75% of data points are found when arranged in increasing order

Interquartile range

measures the spread of the middle half of your data: IQR = Upper Quartile – Lower Quartile = Q­3 – Q­1

Standard Deviation

A measure of the amount of variation or dispersion of a set of values:

σ=√((∑〖(x_i-μ)〗^2 )/N)

Variance

measures variability from the average or mean: (∑〖(x_i-x)〗^2 )/ (n - 1)

Outliers

An observation that lies an abnormal distance from other values in a random sample from a population.

Boxplots

a graphical rendition of statistical data based on the minimum, first quartile, median, third quartile, and maximum

Dot plots

visually groups the number of data points in a data set based on the value of each point

Stacked dot plot

a type of simple histogram-like chart used in statistics for relatively small data sets where values fall into a number of discrete bins

Histograms

a graph that shows the frequency of numerical data using rectangles

Relative histograms

uses the same information as a frequency histogram but compares each class interval to the total number of items

Bin width

the data is graphed in groups of 1 sec times

Modality

describes the number of peaks in a dataset

Unimodal

a probability distribution which has a single peak

Bimodal

Distribution has two peaks

Multimodal

a probability distribution with more than one mode

Skewed right

the long tail is on the right side of the distribution. The higher side is on the left side

Skewed left

the long tail is on the left side of the distribution. The higher side is on the right side

Symmetric

two sides of the distribution are a mirror image of each other

Uniform

a type of probability distribution in which all outcomes are equally likely

Contingency table

a type of table in a matrix format that displays the (multivariate) frequency distribution of the variables.

Bar plots

The pictorial representation of data, in the form of vertical or horizontal rectangular bars, where the length of bars is proportional to the measure of data

Stacked bar plots

a form of bar chart that shows the composition and comparison of a few variables, either relative or absolute, over time

Side by side bar plots

used to display two categorical variables

Standardized Stack bar plots

a type of bar graph that represents the proportional contribution of individual data points in comparison to a total

Segmented bar plots

used to compare two or more categories by using vertical or horizontal bars

Side by side box plots

a visual display comparing the levels (the possible values) of one categorical variable by means of a quantitative variable