finite

5-figure summary of data

-minimum -lower quartile=25% of cumulative frequency=median of lower half of data set -the median -upper quartile= 75% of cumulative frequency=median of upper half -maximum

stratified

the population is first divided into groups. then members are randomly chosen from each group example: A student council surveys 100 students by getting random samples of 25 freshmen, 25 sophomores, 25 juniors, and 25 seniors.

example of continuous data

the time to walk 2 miles

cumulative frequency

total frequency up to a certain data value to find it you divide the frequency by the total number of data values.

interquartile range

IQR= Q3-Q1

right tail calculation

P(X. or = to b)

left tail calculation

P(X< or = to a)

continuous data

data that can take any values within a certain range of real numbers

discrete data

data that can take only certain distinct values, such as whole numbers, or fall into distinct categories.

a survey was conducted of the # of bedrooms in 208 randomly chosen houses. is the data discrete or continuous?

discrete

density curve

graph of a continuous probability distribution. the total area under the curve must = 1 and every point on the curve must have a greater vertical height that is 0 or greater.

probability distribution

graph, table, or formula that gives the probability for each value of the random variable

standard deviation

measures the average distance of all the data points from the mean

conveinience

members are chosen because they are easily accessible example: a researcher polls people as they walk by in the street

simple random sample

members are chosen using a method that gives everyone an equal chance of being selected example: a teacher puts students names in a hat and draws 1

systematic

members are chosen using a pattern, such as selecting every other person example:A principal takes an alphabetized list of student names and picks a random starting point. Every 20th student is selected to take a survey.

self-selected

members volunteer to participate

example of discrete data

the number of dogs in a city

cluster

the population is first divided into groups. a sample of the groups is randomly chosen. all members of the groups are surveyed. example: An airline company wants to survey its customers one day, so they randomly select 555 flights that day and survey every passenger on those flights.