Statistics 1 Flashcards
What is a population
The whole set that are of intrest
What is a sample
some subset of the population intended to represent the population
What is a sampliling frame?
Sampiling untis are individually named and numbered
What is a sampiling unit?
Each individual thing
What are the advantages of a cencus?
- Should give compleatly accurate results
What are the dissadvantages of a census?
- Time consumng
- Expensive
- Cannot use is testing is destructive
- large volume of data to procces
What are the advantages of a sample?
- cheaper
- quicker
- less data to procces
What are the dissadvantages of using a sample?
- Data may not be accurate
- Data may not be large enough to represent small sub-groups
How is simple random sampling carried out?
Each item is given an identity number, then a random number generator is used.
Adv of simple random sampling
- bias free
- easy and cheap
- each number has equal chance of being picked
Disadvantages of simple random sampling.
- not suitable when population size is large
- smapiling frame is needed.
How do you carry out Systematic sampling?
Elements are chosen at regualr intervals in an ordered list
take every K^th number
k = poulation size/ sample size
What are the advantages of Systematic sampling?
- simple & quick to use
- suitable for large samples/poulations
Dissadvantages of using Systematic sampling?
- sample frames needed
- can introduce bias if sampling frame is not random
How do you carry out Stratified sampling?
The population is divided into groups (stratas) and a simple random sample is carried out in each group.
Sample size/population size this proportion is used
How do you carry out quota sampling? Advantages/ dis
Like stratified but strata filled by a reasearcher
-No sampling frame needed
-non-random, potetial bias
How do you carry out sampling
Quota filled by thoses availale at the time
-easy cheep
-unlikely to be representative
What does qualatiative data mean
None numberical, like a colour.
What does quantative data mean?
Numerical, either dicrete or continuous
What are the international stations?
Cambourn
hurn
heathrow
leeming
leuchurs
When was the data set recorded?
May-October 1987- 2015
only six months
What are the international stations
Preth
Beijing, china very sunny and raining in summer, very cold winter
Jacksonville , sunny hurricanes oct 85 oct15
What is 1 Knot equal to? when big storm?
1.15mph great story 0ct15/16 87
What is the advantage of IQR?
It ignores extreams
How do you find varience?
What do you talk about when comparing two graphs?
1) Location
2) Spread (use context)
What is interpolation?
Estimating inside the data range
- usually more reliable.
What is extrapolation?
Estimating outside of the data range
- Not reliable
What is the probability of A Given B?
P (A)
What are the tests of independence?
What is Discrete Uniform Distribution?
Probabilitys of all outcomes are all equal
When do you use binomial Distribution?
Normal distributions
-Point of inflection
-percentages of data in 1 2 and 3 standard deviations of data
what data analasis is not effected by outliers?
median and IQR
