MKC2500 Lecture Notes - Lecture 8: Interquartile Range, Descriptive Statistics, Sampling Distribution
18 Jun 2018
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ETC2500 notes
Target population
• Collection of elements or objects that possess the information the
researcher is seeking; the entire group a researcher is interested in; the
group about which the researcher wishes to draw conclusions
• Usually large and diverse
• Specified according to: time frame, extent sampling unit and element
Sample
• A sample is a subset of the target population, from which we obtain
information
• There are many types of samples, e.g.
o Census
o Non-probability sample (e.g. convenience, judgemental, quota,
snowball)
o Probability sample (e.g. simple random, systematic, stratied, cluster)
Sample Average
Descriptive statistics
Descriptive statistics is about reporting information about the sample distribution
Data tables: frequency histograms, sample distributions, percentage distributions
Measures of central tendency: mean, mode, median
Measures of dispersion: range, interquartile range, deviation scores, standard
deviation, variance
Inferential Statistics
About understanding features of the (target) population distribution
Eg; from the sample we try to infer something about the entire population of value
• Probability sampling enables us to not only draw conclusions about the
target population
