- Qualitative data
- Qualitative (or categorical) data are described by words and are non-numerical, such as blood types or colours.
Ch 01- Categorical data
- Qualitative (or categorical) data are described by words and are non-numerical, such as blood types or colours.
Ch 01- Quantitative data
- Quantitative data take numerical values and are either discrete or continuous.
Ch 01- Discrete data
- Discrete data can take only certain values, as shown in the diagram.
Ch 01- Continuous data
- Continuous data can take any value (possibly within a limited range), as shown in the diagram.
Ch 01- Stem-and-leaf diagram
- A stem-and-leaf diagram is a type of table best suited to representing small amounts of discrete data.
Ch 01- Key
- A key with the appropriate unit must be included to explain what the values in the diagram represent.
Ch 01- Back-to-back stem-and-leaf diagram
- In a back-to-back stem-and-leaf diagram, the leaves to the right of the stem ascend left to right, and the leaves on the left of the stem ascend right to left.
Ch 01- Lower class boundary
- Lower class boundaries are 145.5, 150.5 and 155.5cm.
Ch 01- Upper class boundary
- Upper class boundaries are 150.5, 155.5 and 160.5cm.
Ch 01- Class mid-values
- Class mid-values are (145.5 + 150.5)/2 = 148, (150.5 + 155.5)/2 = 153 and (155.5 + 160.5)/2 = 158.
Ch 01- Histograms
- A histogram is best suited to illustrating continuous data but it can also be used to illustrate discrete data.
Ch 01- Frequency density
- The vertical axis of the histogram is labelled frequency density, which measures frequency per standard interval.
Ch 01- Cumulative frequency
- Cumulative frequency is the total frequency of all values less than a given value.
Ch 01- Cumulative frequency graph
- A cumulative frequency graph can be used to represent continuous data.
Ch 01- Cumulative frequency polygon
- If we are given grouped data, we can construct the cumulative frequency diagram by plotting cumulative frequencies (abbreviated to cf) against upper class boundaries for all intervals. We can join the points consecutively with straight-line segments to give a cumulative frequency polygon.
Ch 01- Cumulative frequency curve
- If we are given grouped data, we can construct the cumulative frequency diagram by plotting cumulative frequencies (abbreviated to cf) against upper class boundaries for all intervals. We can join the points consecutively with straight-line segments to give a cumulative frequency polygon or with a smooth curve to give a cumulative frequency curve.
Ch 01
