statistical sampling 1.1

Question 1

what is population

Answer 1

the whole set of items that are of interest

Question 2

what is sample

Answer 2

some subset of the whole population intended to represent the population

Question 3

what is sampling unit

Answer 3

each individual thing in a population that can be sampled

Question 4

what is a sampling frame

Answer 4

often sampling units of a population are individually named or numbered to form a list

Question 5

what is a census

Answer 5

when you collect data from entire population

Question 6

strength of sample

Answer 6

cheaper
quicker
less data to process

Question 7

weakness of sample

Answer 7

not accurate
not large enough to represent
small sub groups

Question 8

strength of census

Answer 8

should give completely accurate results

Question 9

weakness of census

Answer 9

time consuming
expensive
large volume of data

Question 10

what is simple random sampling

Answer 10

each item is given a number then random number generator selects the number

Question 11

strength of simple random sampling

Answer 11

bias free
easy and cheap
each number has equal chances

Question 12

weakness of simple random sampling

Answer 12

not suitable for large pop
not representative
sampling frame needed

Question 13

what is stratified sampling

Answer 13

population divided into sub groups same proportion to sample as to pop

Question 14

strength of stratified sampling

Answer 14

reflects population
guarantees representation

Question 15

weakness of stratified sampling

Answer 15

population must be in groups
selection within groups

Question 16

what is systematic sampling

Answer 16

people choose at regular intervals e.g.every 100th

Question 17

strength of systematic sampling

Answer 17

simple and quick
suitable for large samples

Question 18

weakness of systematic sampling

Answer 18

sampling frame needed
can be bias

Question 19

what is quota sampling

Answer 19

population divided into groups then opportunity sampling

Question 20

strength of quota sampling

Answer 20

can be representative
no sampling fram
quick easy

Question 21

weakness of quota sampling

Answer 21

bias
must be divided to groups
non response are not recorded

Question 22

what is opportunity sampling

Answer 22

sample taken from people who are available at the time

Question 23

strength of opportunity sampling

Answer 23

easy to carry out
inexpensive

Question 24

weakness of opportunity

Answer 24

not representative
bias