Unitr 1 Analyzing Data

Quantitive Variable

Takes numerical value for a measured of counted quantity. Ex. weight and height

Categorical Variable

Takes on values that are category names or group labels. ex. hair color

Marginal relative frequency

B/C

Joint Relative Frequency

A/C

Conditional Relative Frequency

A/B

Misleading Graph

• Vertical graph must start at 0

• Beware using images for graph

Segmented Bar Graph

Stack bars make 100%

Mosaic Plot

Width is proportional to the group sample size

Association

Occurs when knowing the value of one variable (explanatory variable) helps you predict others (response variable)

• categories have different sizes

Discrete

Countable values, no decimals

continuous

infinite possible values

describing distribution

Shape

Outliers

Center

Variability

SD

SD = sqr root {sum of(x-x)²/n-1}

Mean and SD

non resistant

symmetric distribution

Mean and IQR

resistant

Skewed distribution

1.5 x IQR method

low < Q1 - 1.5(IQR)

high > Q3 + 1.5(IQR)

2 SD Method

low < mean -2SD

high > mean + 2SD

calculator

Stat → Edit → Stat → Calculate → 1 variable stat