Graphical Representation Flashcards
What charts are used for qualitative data?
- Bar chart
- Pie chart
What diagrams are used for quantitative data?
- Histogram
- Scatter diagram
- Time series plot
- Stem and leaf diagram
What are the 3 ways of presenting statistics?
- Words
- Tables
- Graphs
What is the advantage of using words as a method of presenting statistics?
Translates big numbers into things people can understand
What is the advantage of using tables as a method to present statistics?
Easy to understand the numbers that are sitting underneath what you’re saying
What are the advantage of using graphs as a method to present statistics?
Can present large amounts of data
Shows patterns and relationships
What things should you consider when choosing graphs?
- What type of data you have
- What is the data relationship you’re trying to show
- Who are your audience
Why should you avoid 3D graphs?
3D diagrams can give a false interpretation of data being presented because it can make it difficult for the data values to be read accuratley.
It can also make segments of the bar chart look bigger than they are in proportion to other segments making it difficult to compare segments
What number should a bar chart always start at and why?
0!
Provides an accurate picture of the data that it is representing
What data type are bar charts used for?
Qualitative data
On a bar chart, what are the labels on the axis’?
Catagories and frequency
In a bar chart, what is the frequency of a catagory represented by?
The length/height of the corresponding bar
It doesn’t matter if the bars in a bar chart are equal in width and separated by equal spacing.
True or False?
False!
The bars in the chart should be the same width and separated by equal spacing
Describe a grouped bar chart
A seperate bar represents each sub-catagory of data and sub-catagory bars are then grouped together for each category
Describe a pareto chart
A vertical bar chart that displays the bars in rank order of occurance from left to right
Helps identify the most important factors
Describe a stacked bar chart
The bars representing the sub-catagories are placed on top of each other to make a single bar for each category
What data types are pie charts used for?
Qualitative data
What does each segment on a pie chart represent?
A category as a proportion of the whole data set
What is the area of a segment of a pie chart proportional to?
The frequency of its corresponding catagory
How is the angle in each segment of a pie chart calculated?
Relative frequency =
Category frequency/total frequency
Relative frequency X 360
When is a pie chart less useful?
When there are many different catagories because the circle becomes cluttered with small segments
What are the main advantages of using pie charts?
They are easy to construct and simple to understand.
They are visually appealing and therefore attract the attention of the audience
What are the main disadvantages of using pie charts?
They cannot be easily be used to compare proportions of the same catagory in different data sets.
Making a visual comparison of the relative size of segments within a pie chart can also be difficult if perecentage values are not shown.
What data types are histograms used for?
Quantitative data that has been organised into groups or classes
What does the vertical axis of a histogram represent?
The frequency of the classes
How is the frequency of the class represented if there are unequal class sizes in a historgam?
When using unequal class sizes, the frequency of the class will be represented by the area of the corresponding bar
How is frequency represented in a histogram if the classes are the same width?
For classes of the same width, the height of each bar will represent the frequency of the class
How are the bars drawn differently in a histogram compared to a bar chart?
In a histogram, the bars are drawn next to each other without gaps and the width of bars have specific meaning.
Whereas in a bar chart the bars have to be equally spaced apart and all the bars have to be the same width.
What does the horizontal axis of a histogram represent?
The class intervals
What is a scatter diagram?
A graph used to display the value of two quantitative variables so we can observe any potential relationship between them
What does each point on a scatter diagram represent?
A pair of data values for an individual entity
When can a multiple scatter diagram be used?
To compare two different data sets on the same graph
What is a scatter diargam particularly useful for?
Showing whether the data sets contain any extreme values
What data does a stem & leaf diagram represent?
Quantitative
What are the advantages of using a stem & leaf diagram be used?
It is good to observe patterns and highlight interesting features.
Each individual data value is retained.
What are the disadvantages of using a stem and leaf diagram?
It is a time consuming process when there are large data sets.
