ATHK1001 Lecture Notes - Lecture 4: Standard Deviation, Tantrum, Histogram
16 Jun 2018
School
Department
Course
Professor
Lecture 4
Single Figure Summaries of Range
• Standard deviation: roughly the average difference of the observed values
from their means
• Variance: square of standard deviation
Average and Spread
• Measures of average and spread are often given to summarize data
• One without the other is often difficult to interpret
• If XYZ blood component the mean is 122, and the standard deviation is
18, then 134 may not be too bad?
The Normal Distribution
• How do you let a child win at snakes and ladders when it’s a 5/5
chance?
- How much do we have to play to?
- (Want them to win at least once)
• What if we play twice? 25% chance tantrum
• 4 times? 6.25% chance meltdown
• times? Histogram close to the normal distribution called a bell
curve (Gaussian)
• Normal distribution is mathematically what you get when you sum up a
large number of chance events
Interesting Properties of Normal Distribution
• The mean median and mode are the same
• Mean and standard deviation define the distribution
• Can say how many people will fall between scores
• Can state probability of different scores
Precision vs. Accuracy
• Not the same thing
- Precision reflects the exactitude with which something can be stated
- Accuracy is how well the information fits to the truth
• But sometimes precision is used to make something seem accurate
- Digital vs. Analogue bathroom scales
Answer can depend on how you ask the question
• How healthy is the Australian manufacturing
- 2000 to 2012 manufacturing employment down 10%
- But output was up about 10%, exports up 40%
- Focus on what? Employment? Output?
Units of Analysis
- Is globalisation making in income inequality around the planet for better
or worse
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Single figure summaries of range: standard deviation: roughly the average difference of the observed values from their means, variance: square of standard deviation. Average and spread: measures of average and spread are often given to summarize data, one without the other is often difficult to interpret. If xyz blood component the mean is 122, and the standard deviation is. Histogram close to the (cid:498)normal distribution(cid:499) called a bell. 6. 25% chance meltdown curve (gaussian: normal distribution is mathematically what you get when you sum up a large number of chance events. Interesting properties of normal distribution: the mean median and mode are the same, mean and standard deviation define the distribution, can say how many people will fall between scores, can state probability of different scores. Precision reflects the exactitude with which something can be stated. Accuracy is how well the information fits to the truth: but sometimes precision is used to make something seem accurate.
