whats stratified sampling
where population is divided into stratas then a random sample is took from each group
what does stratified sampling allow us to do
take a random sample that represents a population accurately
whats the equation for calculating the number for a strata
strata total/grand total x sample size
whats the pros for stratified sampling
-type of random sampling
-the sample will be representive of the population
whats the cons of stratified sampling
can be time consuming/expensive
may not be possible to have full knowlegde of the population in advance
what way should you think about cumulative frequency
as a running total
whats a population pyramaid
a type of bar chart used to show age or gender structure of a country
what does a chloropleth map use
shading and patterns
whats the equation for a histogram
frequency density = frequency/class width
