Further-Chapter 3- Summarising Numerical Data 2

What is the mean
- balance point of distribution
- = sum of data/total number of data values
- Written as
- _
- x or Ex/n
What is the Standard deviation
Is the spread of data around the mean
- s= square root of E(x- mean)²_/n-1or
- s=r/4
What is is the 68%-95%-99.7% rule
- Normal distribution
- 68% of data within one SD of mean
- 95% of data within two SD of mean
- 99.7% of data withing three SD of mean
What is standardising data
standard score (z)= data value- mean/ SD
- positive score is above mean
- negative score is below mean
- 0 is equal to mean

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jt.mcrae

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Further-Chapter 3- Summarising Numerical Data 2

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Summarising Numerical Data 2

Updated

2011-01-12T04:12:44Z

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