Semester 2 2021
Lecture 2: Summarisation.
This Lecture
• Brief introduction • Data types
• Summarising data via statistical descriptions
• Communicating through visual descriptions of the data
Data Types
Ordinal
small/medium/large; grade or mark H1 H2A H2B; score 50, 83, 96
Nominal/Categorical
Which state or territory you live in: VIC; SA; TAS; NSW; ACT; NT; WA; QLD What city are you travelling from?
Date/Time
Date of birth
Datestamp for a process
Binary
True or false value, eg: Are you a full-time student?
Text
A search query on an e-commerce website: “electric sit-stand desk”
Sequence
New daily cases of covid-19 cases since July 1 2020: 72, 72, 65, 101, 67, 124, 164, 118, 156, 281, .. Winners age grade 40-45 yo mens medium distance: [ , , ]
Numerical Continuous
Distance traveled: 245.7 km
Numerical Discrete
Number of people in each household; Number of students enrolled in a subject…
..
Summarising Data
Describe Data Succinctly
• Provide a mathematical summary of the data
• Mathematical conventions for describing statistical data
• Create a visual summary of the data
• Illustrations of the data gives us a quick snapshot of high-level information • Visual representations are easy to interpret (unlike a large table)
Simple descriptive statistics
• Count (Frequency) • For each category
• Min, Max, Range
• Quartiles, and Percentiles.
• Mean, Median, Mode
• Variance, Standard deviation