Statistics 1 Flashcards
(35 cards)
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
