0331 - Biostatistics I - Sampling - VY Flashcards
What is the difference between probability sampling and non-probability sampling
Probability = determinable change of an individual being sample.Non-probability= non-determinable chance of an individual being sampled.Probability sampling is where the sample is chosen in a way which allows you to determine how likely an individual is to be sampled. Non probability sampling is where the sample is chosen in a way that makes it impossible to determine how likely it is that an individual from the population is included in the samle.
List some descriptions of the central tendency
Mean – the average. Median – the middle point of data where 50% of data points lie above and belowMode - number with the highest frequency
List some measures of data variability
Range, Variance, Standard deviation and Standard error
What is systematic sampling? give an example of systematic sampling
Systematic sampling = sampling from a list where every x individual is chosen (x = any number). E.g. picking every 3rd student in the medical cohort list
What is simple random sampling? Give an example of simple random sampling
Simple random sampling = everyone in population has equal chance of being sample. E.g. putting all the names of ANU students in a hat and randomly drawing
What is stratified sampling ? Give an example of stratified sampling
Stratified sampling = population is divided in strata (subgroups) and random sample is taken from each. E.g. dividing medical cohort into guys and girls and sampling 15 of each
What is cluster sampling? Give an example of cluster sampling
Cluster sampling = cluster (groups) are selected from population and random samples are taken from selected clusters. E.g. surveying residents of Canberra by sampling selected streets in key suburbs
What is convenience sampling? Give an example of convenience sampling
Convenience sampling = using any people that are available for research. E.g. asking medical students who are in front of peter baulme building to do a survey
What is quota sampling?Give an example of quota sampling
Quota sampling = sampling to fill a predetermine quota. E.g. recruiting medical students for a survey until a quota from each academic background is filled
What is purposive sampling? Give an example of purposive sampling
Purposive sampling = selecting individuals based on knowledge of a population, purpose of study and some characteristic of selectees.E.g. Selecting individuals that exemplify a ‘typical med student’
What is snowball sampling? Give an example of snowball sampling
Snowball sampling = existing study subjects recruit other subjects from among their acquaintance..E.g. selecting a few ‘typical med students’ who then ask their friends/colleagues to participate
List some types of probability sampling and non-probability sampling
Probability: simple random, systematic, stratified and cluster samplingNon-probability sampling: convenience, quota, snowball and purposeful sampling
What is nominal data? Is it a discrete or continuous category of data? Give an example
Nominal data = assigning a code to a value or characteristic (number has measurable value). It is a discrete category. E.g. Assigning males = 1 and females = 2
What is ordinal data? Is it a discrete or continuous category of data? Give an example
Ordinal data = assigning a ranked code to a value or characteristic (number has measurable value). It is a discrete category. E.g. how do you feel : 1=good, 2=ok, 3=not great, 4=terrible
What is interval scale? Is it a discrete or continuous category of data? Give an example
Interval scale= scale where distance between adjacent intervals is the same but the zero point is arbitary (does not exist). It is a continuous category. E.g. Measuring temperature (0 degrees does not mean no temperature)
