stat 1

Population

Entire collection of the individuals or objects that we want to learn about

Observational unit

A single member of the population

Sample

A subset of the population that we observe

Parameter

A numerical summary that describes the entire population

Statistic

A numerical summary computed from the sample

Census

Collects information from every unit of the population

Variable

A characteristic measured or recorded for each observational unit

Quantitative variable

Numerical values for which arithmetic has a meaningful interpretation

Categorical variable

Places each observational unit into one of a set of categories

Discrete

When a quantitative variable uses integer numbers

Continuous

When the variable can take any value

Nominal

When category have no natural orderin

Ordinal

When categories have meaningful order

Distribution

Describes what values occur and how frequently they occur for a variable. Measured by center spread and shape

Frequency

Number of observations that fall in that category

Relative frequency

The proportion of observations in that category = category frequency/ total number of observations

In a box plot

Whiskers don’t include outliers and go to the max and min

Suspected extreme

1.5iqr

Probable extreme

Beyond 3 iqr

Sample space

Set of all possible outcomes of a random experiment denoted by s

AuB

All outcomes in a , in b, or in both

AnB

All outcomes that are in both A and B

A^c

All outcomes not in A

Impossible event

$$\phi$$

Disjoint when

AnB =$\phi$

An event

Is an outcome or a collection of outcomes from the sample space, simple if only one outcome, compound if more than one outcome

AcB

Every outcome in A is also an outcome in B so if a occurs then B must also occur

(AnB^c)u(A^cnB)/

One event occurs but the other does not

Probability

A description of how likely an event is to occur

Probability of a given b

P(A|B)

Random variable

Assigns a numerical value to each outcome of a random experiment