Unit 1 Statistics

1.1 Describing, Presenting, and Interpreting Data

Types of Data: there are two types of data.

• Categorical Data: data that can’t be measured, instead the data is grouped by a common characteristic

• Quantitative Data: Data that has some sort of numerical value. There are two types of quantitative data sets.

· Discrete Data: Data that is measured and the values recorded take specific and separated values within a given range. This data is usually the result of counting.

· Continuous Data: Data that is measured and the values recorded can take any value within a given range. This data is usually the result of measuring.

Do exercise 5A 1a-j, 2 (for 1a-f)

Organizing Categorical Data

• Tally and Frequency Table p. 112

Fuel Type	Tally	Frequency
Unleaded Lead Rep LPG Diesel		28 12 8 2
	Total	50

Displaying Categorical Data

• Vertical or Horizontal Bar Graph
• Pie Chart
• Segmented Bar Chart

Organizing Discrete Numerical Data

• Frequency table
• Dot plot
• Stem and leaf plot

Displaying Discrete Data

• Column graph
• Dot plot

Describing the Distribution of the Data Set

• Symmetric
• Negatively Skewed
• Positively Skewed

Stemplot (or Stem-and-leaf plot) is another way of organizing (and displaying) data.

Stem 0 1 2 3 4 5

Leaf 9 7 1 8 3 6 7 6 4 9 3 5 5 6 8 2 1 7 9 3 4 2 1

The stem and leaf plot helps you organize the individual entries by breaking up the number into different columns. At the row 1 | 7 1 means there are entries of 17 and 11 in the data set.

The stem-and-leaf plot is called ‘ordered’ if the entries are, you guessed it, ordered.

Stem 0 1 2 3 4 5

Leaf 9 1 7 3 4 6 6 7 8 1 2 3 5 5 6 8 9 2 3 4 7 9 1

You can group two sets similar data in back to back stemplots.

Ex 1 A swimming squad recorded the times of the latest 100m freestyle practice.

Girls: 35.3, 34.7, 38.6, 36.8, 34.6, 36.8, 36.3, 37.6, 37.7, 36.3, 34.3, 35.7, 35.4, 37.6, 35.8, 37.6, 32.4

Boys: 36.8 32.1 33.2 36.7 33 34.1 34.4 35 35.7 35.9 34.4 35.9 36.8 33.7 34.3 35.4 33.2 37 34.8 35.2

Girls 4 7 6 3 8 7 4 3 0 8 8 3 3 7 6 6 6 6 0

32 33 34 36 36 37 38 39 40 41

Boys 1 0 2 2 7 1 3 4 4 8 0 2 4 7 9 9 7 8 8 0

Remember, context is everything. In this case the leaves represent the first decimal place. Be sure to define somewhere what your units are.

Outliers

• A data entry that is significantly removed from the rest of the data.

p.116#1-6