Statistics
the collection, analysis, representation and interpretation of data
Population
the set from which data is collected
Sample
a subset of the population
Data
quantitative data are numerical
qualitative data are non-numeric
Variables
discrete variable or continuous variable
changing a variable
Types of Frequency
frequency
the nimber of times a data point occurs in the samplerelative frequency
the ratio between the frequency of a data point and the size of the sample (fraction)cumulative frequency
sums up the frequencies to a certain level
# Examples
Test scores of 15 students
$$2,4,1,3,5,4,4,3,5,4,2,6,3,5,4$$
| Frequency | Relative frequency | Cumulative frequency | |
|---|---|---|---|
| 1 | 1 | 1/15 | 1 |
| 2 | 2 | 2/15 | 3 |
| 3 | 3 | 3/15 | 6 |
| 4 | 5 | 5/15 | 11 |
| 5 | 3 | 3/15 | 14 |
| 6 | 1 | 1/15 | 15 |