Statistical Diagrams (Edexcel IGCSE Maths A: Foundation): Flashcards
Exam code: 4MA1
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- FrontTwo-Way Tables
True or False?
A two-way table is used to compare two types of characteristics.
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Cards in this collection (16)
True or False?
A two-way table is used to compare two types of characteristics.
True.
A two-way table is used to compare two types of characteristics.
E.g. school year group and favourite genre of movie.
How do you construct a two-way table from information given in words?
Identify the two characteristics, e.g. favourite colours, gender
Use rows for one characteristic and columns for the other
Add an extra row and column for marginal totals
Red
Blue
Yellow
Total
Male
Female
Total
True or false?
The numbers needed to complete a two-way table will always be given explicitly in a question.
False.
When completing a two-way table, some values can be filled in directly from the question information, but some values will need to be worked out.
E.g. you may need to subtract other values in a row from the row total to find a missing value.
How can you double-check your answers when completing a two-way table?
You can double-check your answers when completing a two-way table by making sure that all row and column totals add up correctly, and that they match the grand total.
How can the probability of an event occurring be worked out from a two-way table?
E.g. what is the probability that a randomly selected student's favourite subject is Physics?
Biology
Physics
Chemistry
Total
Year 7
12
8
10
30
Year 8
8
13
6
27
Total
20
21
16
57
The probability of a particular event occurring can be worked out by finding the number of successes by the total number.
E.g. the probability that a student's favourite subject is Physics is
.Biology
Physics
Chemistry
Total
Year 7
12
8
10
30
Year 8
8
13
6
27
Total
20
21
16
57
A pie chart is drawn for a set of data where the total frequency is 180.
What do you do to the frequency of each item to find its angle for the pie chart?
If a pie chart is drawn for a set of data where the total frequency is 180, you multiply the frequency of an item by 2 (i.e. 360 ÷ 180) to find the size of its angle on the pie chart.
In a pie chart, if you know that the angle 30° represents a frequency of 10, how would you find the total frequency?
In a pie chart, if an angle of 30° represents a frequency of 10, then you can find the total frequency by:
dividing 10 by 30 to find how much 1° represents,
then multiplying this by 360.
Alternatively, you can see how many times 30° goes into 360° and then multiply this by 10.
How do you calculate the angles needed for a pie chart?
To calculate the angles needed for a pie chart:
Divide each frequency by the total frequency.
Multiply each result by 360°.
Alternatively:
Divide 360° by the total frequency.
Multiply each frequency by this number.
If you are given the angles in a pie chart and the total frequency, how do you calculate the individual frequencies?
If you are given the angles in a pie chart and the total frequency, you can calculate the individual frequencies by doing the following:
Divide each angle by 360°.
Multiply by the total frequency.
Alternatively:
Divide the total frequency by 360.
Multiply each angle by this number.
What sorts of things should you look for when reading and interpreting statistical diagrams?
When reading and interpreting statistical diagrams, you should look for:
Keys
Shading
Axis labels
The word "frequency"
Any unusual or unexpected information mentioned
Define anomaly in the context of statistical diagrams.
An anomaly, otherwise known as an extreme value or outlier, is a data point that is significantly different from the rest of the data.
True or false?
You may be asked to comment on aspects of a statistical diagram that could be misleading or incorrect.
True.
You may be asked to comment on aspects of a statistical diagram that could be misleading or incorrect, such as uneven gaps in axis values or a missing key.
Define key in the context of statistical diagrams.
In the context of statistical diagrams, a key is a legend that explains the meaning of symbols, colours, or shading used in the diagram.
True or False?
The purpose of comparing statistical diagrams is to identify and comment on differences or similarities in averages, spread, and unusual data values for the data sets represented by the diagrams.
True.
The purpose of comparing statistical diagrams is to identify and comment on differences or similarities in averages, spread, and unusual data values for the data sets represented by the diagrams.
What should you consider when deciding which measures to compare in statistical diagrams?
When deciding which measures to compare in statistical diagrams, you should consider:
Whether the mean, median or mode is the appropriate average to use.
Whether the range or interquartile range is the appropriate measure of spread to use.
Whether any assumptions or potential issues with the data could affect the reliability of the results and comparisons.
True or false?
You should aim to make at least one pair of comments when comparing statistical diagrams.
False.
You should aim to make at least two pairs of comments when comparing statistical diagrams:
One pair should compare averages and comment on what this means in the context of the question.
The other pair should compare spread and comment on what this means in the context of the question.
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