ap stats 1.1

i shart ed

Descriptive Stats

the methods of organizing & summarizing data

Inferential Stats

involves generalizing from a sample to a population

Variable

any characteristic whose value may change from one individual to  another 

Data

The values for a variable from individual observations

Categorical Data

 Qualitative, describes attributes or Qualities: Would not make  sense to average  

Numerical Data

things you could average  

Discrete

isolated points, things you count

Continuous

Values in an interval, things you measure.

Bivariate Data

2 variables

Multivariate Data

3 or more variables

Categorical Graphs

Bar chart and pie chart, double bar, stacked bar, mosaic  

Numerical Graphs:  

Histograms, boxplots(next chapter), dotplots, stemplots  

Frequency

How often something happens

Relative Frequency

Converting frequency into a percent/proportion 

Percentile

Percent of data at or below a given value

How to describe numerical data distributions 

C (center) Mean, Median 

U (Unusual) Outliers, Gaps, Bimodal 

S (Shape) Skewed, Symmetrical, Uniform 

S (Spread) Range, IQR, Standard deviation, Variance (only Range this chapter) 

B-(Be)  

S- (Specific) 

Comparative Descriptions

Must use comparative language (more, less, etc)  

Cumulative Relative Frequency Graphs (Ogives)

 used to answer questions about  percentiles.