Stats - Unit 1

Science of collecting, organizing, summarizing, and analyzing data to draw conclusions and answer questions

the entire group of people being studied

Subset of population that is being studied

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

a numerical summary of a sample

s=sample

numerical summary of a population

p=pop

Describe data through numerical summaries - tables and graphs

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

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

• 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- 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)

• 1- simple random sampling
• 2- systematic
• 3- stratified
• 4- cluster
• 5- convenience

equal chance for each person or group of people to be picked for the sample

select every k^th individual from the population

EX randomly select a starting point and survey every 5th person

divide population into non-overlapping 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

divide population into non-overlapping groups call clusters - randomly select clusters (not all are chosen) and sample every indivudual

sampling whomever is convenient

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

• Lower- the smallest value within a class
• Upper- the largest value within a class

the difference between consecutive lower class limits

class width = largest data value - smallest data value / number of classes

• -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

• Mean
• Median
• Mode

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

• x bar computed using sample data
• samp mean = statistic