186817
Descrição
Mapa Mental por shirley.ha, atualizado more than 1 year ago
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Criado por shirley.ha
aproximadamente 11 anos atrás
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Prob Methods of sampling
- Probability
- more likely to be representative of the
population from which they are drawn than
non-probability samples.
- likelihood that a participant
is included in the sample is
known for each subject in
the population.
- More commonly used
- likelihood that a participant
is included in the sample is
known for each subject in
the population.
- Simple random
- each member of the population has an equal
and independent chance/probability of being
selected into the sample
- Important principles
- members of the population are
selected one at a time
- independent of each other and
without replacement
- independent of each other and
without replacement
- members of the population are
selected one at a time
- i.e lottery draw iplacing each
possible number in a container
and selecting one at a time
without looking until the
desired number is reached.
- each member of the population has an equal
and independent chance/probability of being
selected into the sample
- Systematic
- dividing the sampling frame into a
number of intervals, randomly selecting a
starting point and then selecting one
element from each interval in a systematic
way.
- arranged in such a way that bias is
introduced into the sample selection
process.
- i.e class list contains sub-groupings of
individuals whereby some members of the
sub-groups are never selected.
- i.e class list contains sub-groupings of
individuals whereby some members of the
sub-groups are never selected.
- may select every 10th person on
the sampling list.
- sampling frame is a class list arranged
in alphabetical order by surname
- decide to select every fourth name on the list
- a starting point is randomly selected between one
and four and then every fourth element is selected
- Sample frame= divided into
intervals of four elements
- a starting point is randomly selected between one
and four and then every fourth element is selected
- sampling frame is a class list arranged
in alphabetical order by surname
- dividing the sampling frame into a
number of intervals, randomly selecting a
starting point and then selecting one
element from each interval in a systematic
way.
- more likely to be representative of the
population from which they are drawn than
non-probability samples.
- Cluster
- whole population being divided into groups or
clusters and then a certain number of clusters
are randomly sampled using simple, systematic
or stratified random sampling.
- i.e geographic area, hospitals, schools
- required number of clusters
is selected you then sample
all units within the clusters.
- interested in obesity in primary school
aged children in Victoria.
- create a sampling frame of all Victorian primary
schools and then randomly select clusters or
schools
- would then invite all children to participate in the study.
- would then invite all children to participate in the study.
- create a sampling frame of all Victorian primary
schools and then randomly select clusters or
schools
- interested in obesity in primary school
aged children in Victoria.
- required number of clusters
is selected you then sample
all units within the clusters.
- very economical method of sampling.
ABS uses cluster sampling to collect data
for the National Health Survey.
- whole population being divided into groups or
clusters and then a certain number of clusters
are randomly sampled using simple, systematic
or stratified random sampling.
- Stratified
- involves dividing the population into
groups (for example, age)
- calculating the number of participants needed in
each group or strata so that the numbers reflect
their proportion in the population.
- ensures that important sub-groups are
identified proportionally prior to random
sampling.
- i.e in many community surveys people
from some ethnic groups are
under-represented.
- Conduct a community survey and want Italian
population in a certain area where 20% are. So
ensure that 20% are included in the survey to be a
accurate rep.
- Conduct a community survey and want Italian
population in a certain area where 20% are. So
ensure that 20% are included in the survey to be a
accurate rep.
- i.e in many community surveys people
from some ethnic groups are
under-represented.
- randomly selecting participants into each stratum.
- involves dividing the population into
groups (for example, age)
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