
Statistics (the study of)
Science of collecting, organizing, summarizing, and analyzing data to draw conclusions and answer questions

Population
the entire group of people being studied

Sample
Subset of population that is being studied

Individual
A person or object that is a member of the poopulation being studied

Statistic
a numerical summary of a sample
s=sample

Parameter
numerical summary of a population
p=pop

Descriptive Statistics
Describe data through numerical summaries  tables and graphs

Inferential Statistics
Take a result form a sample  extend to the pop  measure reliability of result

Variable
 Characteristics of the individual within a population
 EX weight, height, age

Qualitative vs. Quantitative
 Qualitative classification based on a characteristic (gender, eye color)
 Quantitative numerical measurements of individuals (age, weight, shoe size)
Difference is when added together, one means something, and the other does not or cannot be added together

Discrete vs. Continuous
 Discrete an infinite # of values that are countable (# of facebook friends  cannot have half a fb friend)
 Continuous an infinite # of values that are not countable (weight, age  can weigh 110.5 lbs)

What are the 5 types of sampling?
 1 simple random sampling
 2 systematic
 3 stratified
 4 cluster
 5 convenience

Simple Random Sampling (SRS)
equal chance for each person or group of people to be picked for the sample

Systematic
select every k^{th} individual from the population
EX randomly select a starting point and survey every 5th person

Stratified
divide population into nonoverlapping homogenous groups  randomly select sample from every strata
EX divide class into 2 strata (shoes & boots) then randomly select 10 students from each group = sample

Cluster
divide population into nonoverlapping groups call clusters  randomly select clusters (not all are chosen) and sample every indivudual

Convenience
sampling whomever is convenient

Histogram
 Constructed by drawing rectangles for each class of data  height of rectangle is the frequency of the class.
 Same width and always touching

Lower vs. Upper limit
 Lower the smallest value within a class
 Upper the largest value within a class

Class Width
the difference between consecutive lower class limits
class width = largest data value  smallest data value / number of classes

Stem and Leaf Plot
 represent quantitative data graphically
 numbers on the left (stem) represent the first few digits
 number on the right (leaf) represent the last few digits
 leaves are stacked on the right side

What are the measures of central tendency?

Population arithmetic mean
 μ computed by using all of the individuals in a population
 pop mean = paramater

Sample arithmetic mean
 x bar computed using sample data
 samp mean = statistic

