Chapter 2 Flashcards
What is the cumulative frequency?
The cumulative frequency of the value of a variable is the total number of observations that are less than or equal to that value
If data are widely spread they should be grouped into what?
Classes
When might class intervals vary in width?
When there is an uneven spread of data across the range
When may the first and/ or last intervals be left open?
When the extreme values if data are not known
What do two-way tables display?
Displays frequencies for two categories of data
What is a database?
An organised collection of information
What does a summary table show?
Shows data that have been sorted and summarised. It is easier to interpret than original data
What does a pictogram use?
Uses symbols or pictures to represent a certain number of items
What must a pictogram have?
A key to yell you the number of items represented by a single symbol or picture
When drawing a pictogram, make sure that:
Each picture is the same size
The picture can be divided easily to show different frequencies
The spacing between the pictures is the same in each row
You give a key
Describe bar charts
In a bar chart, bars of equal width are drawn for each category or quantity
The length of a bar is equal to the frequency of the category it represents
The gaps between bars must be of equal width
How are bar charts and vertical line graphs different?
A vertical line graph is similar to a bar chart except that the bar width is reduced to a pencil line thickness
What does a stem and leaf diagram show?
A stem and least diagram shows the data distribution in the same way as a bar chart but it retains the details of the data
In a stem and leafy diagram, what does the key show?
A key shows how the stem and the leaves are combined to form a number
What is a pie chart?
A pie chart is a way of displaying data when you want to show how something is shared or divided. It uses area to represent frequency. The angles at the centre of a pie chart adds up to 360 degrees
