Bryman Chapter 8: Sampling in quanttatie reeearch
o In order to generalize fndinge a eample neede to be repreeentatie
o Biaeed Sample: A eample that doee not repreeent the populaton rom which it wae eelected;
The choice o the eample wae infuenced by pereonal judgement and other external actore
o Non-probability or non-random eampling method, inadequate eampling rame, non-
reeponee lead to biaeed eamplee
Typee o probability eample
o Simple random eample
Moet baeic orm
Each unit o the populaton hae an equal chance to partcipate in the euriey
Probability o inclueion in the eample: Number o indiiiduale in a eample diiided by
n
the total number o indiiiduale in the populaton eampling ractonn
N
Key etepe: defne the populaton; Select a eampling rame; Decide eample eize; Aeeign
all membere o the populaton a number; uee a program that generatee random
numbere
No opportunity or human biae to inter ere in the eampling collecton proceee
o Syetematc eample
Selecton o membere directly out o the eampling rame
Syetematc choice, eiery 20th indiiidual out o the eampling rame ie choeen
o Stratfed random eampling
Proportonal repreeentaton
Stratfcaton o the populaton by a criterion e.g. memberehip o a acultyn
Selecton o eimple random eample or eyetematc eample rom the reeultng etrata
Only poeeible i unite are eaey to ident y and aeeign to a etrata
More than one etrat ying criteria can be ueed
o Mult-etage clueter eampling
Clueter: Groupe o unite o the populaton in queeton o reeearch
Mult etage approach
Probability eampling method neede to be employed at each etage: eampling o
cluetere and then eampling o indiiiduale or urther clueter
Allowe or high geographic concentraton
Sample Size
o Abeolute and relatie eample
The abeolute eize o a eample ie important, not the relatie eize
Increaeing the eize o a eample increaeee the likelineee that it will be preciee
Increaeed eample eize Decreaeed eampling error
o Time and coet
Coneideratone o the eample eize are ofen aaected by tme and coet matere
o Non-reeponee
Unit non-reeponee: membere o the eample re uee to partcipate or are not
contactable
Item non-reeponee: membere agree to partcipate but ail to deliier anewere to all
queetone itemen
Reeponee ratee can be increaeed, howeier thie ie ofen expeneiie
o In order to generalize fndinge a eample neede to be repreeentatie
o Biaeed Sample: A eample that doee not repreeent the populaton rom which it wae eelected;
The choice o the eample wae infuenced by pereonal judgement and other external actore
o Non-probability or non-random eampling method, inadequate eampling rame, non-
reeponee lead to biaeed eamplee
Typee o probability eample
o Simple random eample
Moet baeic orm
Each unit o the populaton hae an equal chance to partcipate in the euriey
Probability o inclueion in the eample: Number o indiiiduale in a eample diiided by
n
the total number o indiiiduale in the populaton eampling ractonn
N
Key etepe: defne the populaton; Select a eampling rame; Decide eample eize; Aeeign
all membere o the populaton a number; uee a program that generatee random
numbere
No opportunity or human biae to inter ere in the eampling collecton proceee
o Syetematc eample
Selecton o membere directly out o the eampling rame
Syetematc choice, eiery 20th indiiidual out o the eampling rame ie choeen
o Stratfed random eampling
Proportonal repreeentaton
Stratfcaton o the populaton by a criterion e.g. memberehip o a acultyn
Selecton o eimple random eample or eyetematc eample rom the reeultng etrata
Only poeeible i unite are eaey to ident y and aeeign to a etrata
More than one etrat ying criteria can be ueed
o Mult-etage clueter eampling
Clueter: Groupe o unite o the populaton in queeton o reeearch
Mult etage approach
Probability eampling method neede to be employed at each etage: eampling o
cluetere and then eampling o indiiiduale or urther clueter
Allowe or high geographic concentraton
Sample Size
o Abeolute and relatie eample
The abeolute eize o a eample ie important, not the relatie eize
Increaeing the eize o a eample increaeee the likelineee that it will be preciee
Increaeed eample eize Decreaeed eampling error
o Time and coet
Coneideratone o the eample eize are ofen aaected by tme and coet matere
o Non-reeponee
Unit non-reeponee: membere o the eample re uee to partcipate or are not
contactable
Item non-reeponee: membere agree to partcipate but ail to deliier anewere to all
queetone itemen
Reeponee ratee can be increaeed, howeier thie ie ofen expeneiie
