sampling test Flashcards
whole group of individuals or items of interest
population, N
(all college students in the ph)
population from which a sample will actually be taken
sampling population, n
(students at 3 specific universities in the ph)
group of which representative information is desired and to which inferences will be made
target population
(all teens who uses social media)
individual elements in a population being studied
sampling unit/ study unit
*it can be a person, fam, city, hospital, clinic, object
(indiv teenagers, social media, post)
list of elements in the sampling population
sampling frame
(complete list of all students in school)
an object or person on which a measurement is actually taken/ observation is made
elementary unit/ element
(SPECIFIC person/ thing you actually collect from the data)
difference between the vale of the parameter being investigated
sampling error
*sample shows vs actually there
sampling unit vs elementary unit
sampling units:
contain many elementary units
*it can be a person, fam, city, hospital, clinic, object
(classrooms)
elementary unit:
basic unit on actual observation is made
(individual students)
it is the act of studying or examining only a part of the total population
sampling
advantages of sampling
Cheaper
Faster
Better quality of information
More comprehensive data
Only possible method for destructive procedures
what are the use of sampling in public health
Evaluation of the health status of a population.
Investigation of factors that may affect health.
Evaluation of the effectiveness of health measures.
Assessment of specific aspects in the administration of health services.
Criteria of a Good Sampling Design
The samples obtained should be representative of the population. Meaning it should reflect both the characteristics as well as the variability of the population being studied.
Sample size should be adequate.
too few = misleading
too many = waste resources
Practicality and feasibility of the sampling procedure.
Economy and efficiency of the sampling design. (must get most info at the smallest cost)
what r the 2 types of sampling designs
probability
non-probability
in non-probability, what is the probability of each member of the population being selected in the sample
it is difficult to determine/ cannot be specified
no way to assess the reliabily of the sample results
true or false:
in non-probability, standard errors can be computed and methods of statistical inference cannot be applied.
false - cannot
explain why results based on non-probability sampling designs are best utilized only for descriptive purposes
u can describe what you found in your sample but u cant make confident predictions abt the whole population
nonprobability is used when studying
hidden population (homeless, drug users, prostitute)
*snowball technique
A representative sample of the population is selected based on an expert’s subjective judgment or on some pre-specified criteria.
Judgment or purposive
*most common type
Sometimes a researcher may use in the study whatever items come at hand or whoever is available.
Accidental/ haphazard sampling
Data collectors are given quotas to meet. They will keep on interviewing until the pre-specified quota meets.
Quota sampling
most basic type of probability sampling design.
simple random
main difference between probability and non-probability sampling designs
Probability sampling: The rules for picking a sample are clear and specific. Every individual in the population has a known, non-zero chance of being selected. This allows for more accurate predictions about the entire population.
Non-probability sampling: The rules aren’t as strict or well-defined. Some individuals may not have any chance of being chosen, so it’s harder to make predictions about the whole population.
In simple terms, probability sampling is more structured and fair, while non-probability sampling can be more flexible but less precise.
main characteristics of simple random
every element in the population has an equal chance of being included in the sample.
an alternative way for simple random
to number the population members chronologically. The numbers of those who will be included in the sample are selected by using a table of random numbers.
*chronologically numbered listing of the population is required to serve as the sampling frame.
simple random is used in
systematic sampling is used when
surveys involving relatively small population with readily available sampling frames
Used when the sampling units are too numerous to number for purposes of SRS (simple random)
Is a variation of simple random sampling.
systematic sampling
how is the sampling interval is first determined in systematic sampling
k= N/n
Example: a sample of 10 households is desired from a community with 80 households.
80/10 = 8 (sampling interval)
This means that one household will be included in the sample for every 8 households in the population.
Now we have determined our k. We will now pick one number from 1tok.
Example we picked number 5. (starting point)
The 5th household will be the 1st to be interviewed and will add 8 to know who will be the next.
13, 29, 37, 45, 53, 61, 69 and 77
population is first divided into overlapping groups called subgroups
Stratified Random Sampling
*strata
It is used when a sampling frame for elements is not readily available or when cost considerations are important.
cluster sampling
It is used when the sample survey has a wide coverage.
Multi-stage Sampling
it is a cluster of elements
sampling units
- Population is 1st divided into clusters that serve as the sampling units and a sample of units is selected.
Every element found in each sampling unit drawn as a sample may or may not be included in the study.
[once clusters r selected, u may include all indiv frm selected or only some indivs from each selected clusters
process of Multi-stage Sampling
The population is1st divided into a set of primary or first stage sampling units.
Each primary sampling unit included in the sample is further subdivided into secondary or second stage sampling units from which sample will again be taken.
The procedure continues until the desired stage is reached.
