Presenting Logical & Reasoned Arguments (AQA Level 3 Mathematical Studies (Core Maths))

Revision Note

Jamie Wood

Expertise

Maths

Criticising Arguments & Claims

How do I criticise an argument or claim mathematically?

  • A thorough argument should be backed by mathematical or statistical evidence, with clear reasoning linking to the conclusion

  • However, this is not always the case for claims or arguments that are made

  • In an exam, you may be asked to do any of the following:

    • Critically analyse

      • Look for and identify errors, suggest improvements and evaluate

        whether a claim is justified

    • Comment on

      • Describe one or more notable feature(s) of the situation in the

        question

    • Comment on the validity of

      • Determine if there is evidence to support the claim

    • Justify

      • Give working or reasons to support your answers

  • When criticising a claim or argument you must be as objective as possible

    • Use the data or information in front of you only

    • Quote the data accurately to help justify your own argument

  • Consider the limitations and scope of the data

    • If something is true in this sample, is it necessarily true for the population?

Worked Example

Basil, a hotel manager, is investigating the number of different drinks consumed each day at breakfast. The hotel serves breakfast every day and Basil conducts a survey on Friday, Saturday, and Sunday.

Basil produces the composite bar chart below, showing the number of cups of coffee, tea, and fruit juice consumed on Friday, Saturday, and Sunday.

composite bar chart showing coffee, fruit juice, and tea, consumed for Friday, Saturday, and Sunday

(a) Basil claims that the most popular drink consumed on Sunday is coffee.

Comment on his claim.

Use the evidence from the composite bar chart, only considering Sunday

The lowest section of the graph in grey, shows the number of cups of tea consumed

150 cups of tea

The height of the middle (striped) section shows the number of cups of fruit juice consumed

350 - 150 = 200 cups of fruit juice

The height of the top (black) section shows the number of cups of coffee consumed

500 - 350 = 150 cups of coffee

Calculate a statistic to help evidence your argument
E.g. Coffee as a percentage of all drinks on Sunday

150 ÷ (150 + 150 + 200) = 0.3 = 30%

And for fruit juice

200 ÷ (150 + 150 + 200) = 0.4 = 40%

Comparing the figures for Sunday, coffee only represents 30% of drinks consumed, which is the same percentage as tea

Fruit juice however is the most popular, with 40% of drinks consumed on Sunday

(b) Sybil, another manager at the hotel, claims that

"According to the data, fruit juice is the most popular drink each week".

Assess the validity of Sybil's claim.

Calculate the total number of drinks consumed of each type for Friday, Saturday, and Sunday

Tea: 100 + 150 + 150 = 400

Fruit Juice: 150 + 200 + 200 = 550

Coffee: 100 + 100 + 150 = 350

Sybil's claim is true for Friday, Saturday, and Sunday, this week
However, her claim is further-reaching than this
She claims it is true "each week" which we do not have data for

Whilst Sybil's claim is valid for the sample shown, 3 days across one particular week, it does not have statistical evidence for the rest of this week, nor multiple weeks

So the claim that fruit juice is the most popular drink every week is not valid with the data provided

However, more samples, for more days and weeks, could be collected to investigate this claim

Exam Tip

The majority of marks on these questions are for the mathematical methods, rather than the final conclusion or assessment made about the claim.

So make sure your working is clear, and label what it is you are working out.

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Jamie Wood

Author: Jamie Wood

Jamie graduated in 2014 from the University of Bristol with a degree in Electronic and Communications Engineering. He has worked as a teacher for 8 years, in secondary schools and in further education; teaching GCSE and A Level. He is passionate about helping students fulfil their potential through easy-to-use resources and high-quality questions and solutions.