6. Which of these is an example of a 3rd party who produces secondary data?

7. Which of these is an example of data available on commercial databases?

non-probability method based on judgement, often associated with convenience sampling. Eg a researcher may draw the entire sample from one “representative” part
Every Nth record is selected from a list of population numbers. MUST not contain any hidden order. Simpler version of random sampling
Useful when the certain characteristics is only a small part of the population but we want to ensure its representation. identify charactersitcs of the population that are already known then select a random sample to represenet those characteristics.
Purest form of probability sampling, with each member of the population having an equal (& known) chance of being selected

can take any value in an interval on the line from minus infinity to plus infinity
takes only a finite number of values
data which is places in an order or scale but each number will convey special info

Useful when the certain characteristics is only a small part of the population but we want to ensure its representation. it reduces sampling error (possibility of selecting an unrepresentative sample)
Convenience matters over cost or time required to select a proper random sample.
each member of the population having an equal (& known) chance of being selected
non-probability method based on judgement. esearcher may draw the entire sample from one “representative” part . Confidence about the sample is needed.
Every Nth record is selected from a list of population numbers. – useful for selecting specified number of records from a computer file.

data which is places in an order or scale. But each order of these numbers will convey info, for example a grade A, B C.
can take any value in an interval on the line from minus infinity to plus infinity
takes only a finite number of values eg how many companies there are on the FTSE 100.

based on convenience
Used if the desired sample characteristics are very rare. Reliance on referrals from initial subjects to generate additional sample info, hence reduction in costs while introducing bias since it’s less likely that the sample will represent a good cross-section from the overall population
non-probability equivalent of stratified sampling - characteristics need to be identified and their proportions BUT Convenience or judgement sampling is then used to select the required number of subjects.
non-probability method based on judgement, often associated with convenience sampling. Eg a researcher may draw the entire sample from one “representative” part

non-probability method based on judgement, often associated with convenience sampling.
based on convenience
used if the desired sample characteristics are very rare. Reliance on referrals from initial subjects to generate additional sample info, hence reduction in costs while introducing bias since it’s less likely that the sample will represent a good cross-se
non-probability equivalent of stratified sampling

used if the desired sample characteristics are very rare
Often used instead of random sampling. Every Nth record is selected from a list of population numbers. MUST not contain any hidden order.
Useful when the certain characteristics is only a small part of the population but we want to ensure its representation. identify charactersitcs of the population that are already known then select a random sample to represenet those characteristics.
Purest form of probability sampling, with each member of the population having an equal (& known) chance of being selected