STAT150 Lecture Notes - Lecture 1: Simple Random Sample, Selection Bias, Response Bias
18 May 2018
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STAT150 LECTURE – 28/2/18
WK1
Statistics is the science of learning from data which involves collecting, presenting, analysing
and interpreting data.
OBJECTIVES AND SCOPE OF STATISTICS
A primary objective of the statistician is to obtain information about a target population,
using a sample.
o The target population comprises all relevant subjects of interest
o The sample is a manageable subset, selected to make study feasible
WHY TAKE A SAMPLE?
To study a population without being hindered om examining a larger group of people. It
allows data to be more accessible.
STUDY DESIGN
- Formulate the question of interest
- Specify the target population
- Determine the measurements to be collected (variables)
POPULATION AND SAMPLES
- The target population should be well defined.
- The sample should be representative of the target population (not biased), and large
enough to give accurate information about the population.
Ideally observations should be independent of each other. Each subject should be
independent and representative.
o ONLY a representative sample should be used to make inferences about the target
population
o A representative sample is unbiased and large enough to give accurate information
about the population
o A way to ensure a sample is representative of the target population is to obtain a
random sample
o A simple random sample is one where each member of the target population has an
equal chance of being chosen, e.g. drawing names out of a hat
It is often difficult or even impossible, to obtain a simple random sample due to limitations.
However, researchers should always try to obtain a representative sample of the target
population.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Statistics is the science of learning from data which involves collecting, presenting, analysing and interpreting data. A primary objective of the statistician is to obtain information about a target population, using a sample: the target population comprises all relevant subjects of interest, the sample is a manageable subset, selected to make study feasible. To study a population without being hindered om examining a larger group of people. Determine the measurements to be collected (variables) The target population should be well defined. The sample should be representative of the target population (not biased), and large enough to give accurate information about the population. Ideally observations should be independent of each other. It is often difficult or even impossible, to obtain a simple random sample due to limitations. However, researchers should always try to obtain a representative sample of the target population. An observational study is one in which there is no intervention by the investigator nor there is any treatment imposed.
