Biostatistics 1300

Individual

An object described by a set of data (ex. random bird)

Variable

A characteristic about an individual (ex. wingspan, beak length, color)

Population

A group of all individuals of interest (ex. all the students in CPP)

Parameter

A number that describes an aspect of the population (ex. average age of students)

Sample

A subset of the population (ex. all students in STA1300 at CPP)

Statistic

A number that describes an aspect of the sample (ex. average age of students in 1300 Statistic)

Categorical (Qualitative) Variables

Place variable into categories.

Qualitative Nominal Variables

Have no natural order (ex. names, colors, gender, shoe type)

Qualitative Ordinal Variables

Have some sort of natural order (ex. t-shirt size, shoe size, height classification, alphabet)

Numeric (Quantitative) Variables

Are variables that are numbers and make sense to do math on.

Quantitative Discrete Variables

Are countable and have gaps between possible values (ex. how many languages you speak, number of friends, number of pets)

Quantitative Continuous Variables

Can be any number in an interval (ex. height, weight, earthquake magnitude, length, temperature)

Frequency

A number of times a value appears in a data set.

Frequency distribution

Tabulation (make it a table) of the frequencies.

Relative frequency

Is the proportion of times a value appears in a data set.

Pareto chart

When a bar graph is ordered from most to least frequent.

Histograms

Like bar plots for numeric data where the 'categories' are called classes or bins.

Lower class limit (LCL)

Smallest value that can appear in a class.

Upper class limit (UCL)

Largest value that can appear in a class.

Class width (CW)

Difference between 2 consecutive LCLs.

Measure of center

Mean, Median.

Mean

Add up all values and divide by how many there are.

Median

Is the center of a sorted data set.

Standard deviation (SD)

Is the average spread of the data around the mean.

Percentile

Is the value such that p% of the data is equal to or less than that value.

LOB

Lower outlier bound.

UOB

Upper outlier bound.

Outlier

Any number smaller than the LOB or larger than the UOB.