Week 5 - Understanding Statistical Uncertainty Flashcards
Define ‘Frame’?
a list of the items in the population of interest.
Define ‘Non-probability sample’?
one where selection is not based on known probabilities
Define ‘Convenience sampling’?
selection using a metod that is easy or inexpensive.
Define ‘Judgement sample’?
gives the opinions of preselected experts.
Define ‘Probability sample’?
one where selection is based on known probabilities.
Define ‘SImple random sample’?
one where each item in the frame has an equal chance of being selected.
What is ‘Sampling with replacement’?
An item in the frame can be selected more than once
Define ‘Sampling without replacement’?
each item in the frame can be selected only once.
What is a ‘table of random numbers’?
shows a list of numbers generated in a random sequence.
Define ‘Systematic sample’?
a method that involves selecting the first element randomly then choosing every kth element thereafter.
Define ‘Stratified sampleing’?
items randomly selected from each of several populations or strata
Define the term ‘Strata’?
subpopulations composed of items with similar characteristics in a stratified sampling design
Define ‘Cluster sampling’?
The frame is divided into representative groups (or clusters), then all items in randomly selected clusters are chosen.
Define the term ‘Cluster’?
a naturally occurring grouping, such as a geographical area.
What are the 4 errors that surveys are subject to?
- Coverage error
- Non-response error
- Sampling error
- Measurement error
Define ‘Coverage error’?
occurs when all items in a frame do not have an equal chance of being selected. This causes selection bias.
Define ‘Non-response error’?
occurs due to the failure to collect information on all items chosen for the sample; this causes non-response bias.
Define ‘sampling error’?
the difference in results for different samples of the same size.
Define ‘measurement error’?
the difference between survey results and the true value of what is being measured.
Define ‘Sampling distribution’?
The probability distribution of a given sample statistic with repeated sampling of the population.
Define ‘Sampling distribution of the mean’?
the distribution of all possible sample means from samples of a given size for a given population.
Define the term ‘unbiased’?
if the average of all possible means equal the population mean then the sample mean is unbiased
Define ‘Standard error of the mean’?
reflects how much the sample mean varies from its average value in repeated experiments.
