data collection chapter 1

Question 1

what is a sampling frame

Answer 1

a list of people or things that you are sampling.

Question 2

what is a census

Answer 2

measure of every member of population

Question 3

advantages and disadvantages of census

Answer 3

+ accurate
- expensive and time consuming

Question 4

what is simple random sampling

Answer 4

a simple random sample of size n is one where every sample of size n has an equal chance of being selected

requires a sampling frame . each person or thing is allocated a unique number and a selection of these numbers is chosen at random.

Question 5

what are the advantages and disadvantages of simple random sampling

Answer 5

+ no bias because it is random
- sampling frame is required

Question 6

what is systematic sampling

Answer 6

the required elements are chosen at regular intervals from an ordered list

eg. if sample size fof 20 is required from a population of 100, then you do 20/100, giving you 5. so then take every 5th number

Question 7

what are the advantages and disadvantages of systematic sample

Answer 7

+ quick to use
- sampling frame required

Question 8

what is stratified sampling

Answer 8

the population is divided into mutually exclusive strata (males and females eg) and random sample taken from each

number sampled in stratum = (number in stratum/number in pop) x overall sample size

Question 9

advantages and disadvantages of stratified sampling

Answer 9

+ reflects population
- population must be classified

Question 10

what is quota sampling

Answer 10

an interviewer or researcher selects a sample that reflects the characteristics of the whole population

Question 11

advantages and disadvantages of quota sampling

Answer 11

+ no sampling frame
- bias (because it is not random)

Question 12

what is opportunity sampling

Answer 12

consists of taking the sample from people who are available at the time the study is carried out and who fit the criteria you are looking for

Question 13

what are the advantages and disadvantages of of opportunity sampling

Answer 13

+ easy/cheap
- unlikely to be representative

Question 14

what are the two types of data

Answer 14

qualitative : non-numerical eg colour, words

quantitative : numerical
- discrete : fixed value
- continuous : any value in range

Question 15

for the large data set, what months is the data recorded

Answer 15

may to october 1987
may to october 2015

Question 16

what are the 5 stations for the large data set that are in the UK

Answer 16

• leuchars
  -leeming
• heathrow
• hurn
• camborne

Question 17

what are the 3 international stations for the large data set

Answer 17

• jacksonville
• beijing
• perth

Question 18

what are the only data recorded for overseas stations in l.d.s

Answer 18

• daily mean temp (degrees celcius)
• daily total rainfall (mm)
• daily mean pressure (hPA)
• daily windspeed and direction (knots)