Chapter 1: Representation of data Flashcards
How many types of data are there and what are they called?
Two. Qualitative and Quantitative.
What is qualitative data?
Non-numerical data, which is described by words. Also known as categorical data.
What is quantitative data and what are the types?
Numerical and are either discrete or continuous.
What is discrete data? What is continuous data?
Discrete data can be counted and cannot be made more precise. Continuous data is a measurement given to a degree of accuracy.
What is a stem-and-lead diagram?
It is a diagram best suited for small amounts of discrete data. A stem-and-leaf diagram has the diagram itself and a key.
What are the aspects of a histogram?
A histogram has no gaps as numbers are rounded and lower and upper boundaries separate the classes. To build a histogram a grouped frequency density table is used.
How to build a grouped frequency density table?
Continuous data is rounded and classes are created. Each class has a frequency (number of data points in this class). For each class class width is calculated. This is then used to calculate frequency density.
What is the formula for frequency density?
Frequency density = class frequency / class width
What is the assumption we have to make by using histograms?
That the values are spread out evenly across the whole class interval.
What is a cumulative frequency?
It is the total frequency of all values less than a given value.
How to construct a cumulative frequency graph?
Continuous data should be rounded and class intervals with cumulative frequency set up. A frequency is plotted against the graph at the upper class boundary.
What are the best data representations for ungrouped discreet quantitative data?
Pictogram, vertical line graph, bar chart, pie chart, sectional bar chart.
For groups discrete quantitative data?
Depending on the amount. Small - stem-and-lead diagram. Large - Histogram or Cumulative frequency graph.
For continuous data?
Histogram and Cumulative frequency graph.
