stats stuff Flashcards
(20 cards)
What is simple random sampling?
- Number all items in population
- Random numbers to select a sample
What is systematic sampling?
- Number all items
- n = population size/sample size
- random num from 1-n to select first item
- choose every nth item after that
What is stratified sampling?
- Divide population into groups
- Decide how many to sample from each group by:
num in group/num in population x sample size - use simple random sampling
NON RANDOM:
Opportunity sampling - what is it?
Sample is any items available to be sampled
NON RANDOM:
What is quota sampling?
Divide population into groups - sample items until number from each group has been sampled?
total people in group/total people overall x sample size
What is PMCC?
It provides information on the type & strength of the correlation between the two variables.
What is causal correlation?
When a change in one variable affects the other
What is correlation without a causal connection?
Spurious correlation
Hypothesis testing - what is your null hypothesis?
What is the 2nd hypothesis for a one tail test?
What is 2nd hypothesis for a two tail test?
What is standard deviation?
Square root of variance
With linear interpolation, what are we assuming?
Data is spread out evenly in a linear pattern within each group.
What months does the large data set cover?
May to October
What are the colder months (for everywhere except australia)
Jan, Feb, Dec
What are the hotter months (everywhere except australia)?
Aug, Jun, Jul
From North - South where is the LDS places
Leuchars
Leeming
Heathrow
Hurn
Camborne
Cleaning data?
If we have any n/a, we don’t use it, cleaning data is just removing that entry
Beijing key features
- Colder winters
- Hotter summers
Jacksonville key features?
Hot summers
Hurricanes in October
