Skip to content

Analysing Interpreting Project Data Class 11 Economics

questionbuddy.in/cbse/class-11/economics/use-of-statistical-tools/analysing-and-interpreting-project-data

EconomicsCBSE Class 11 · Use of Statistical Tools

Analysing and Interpreting Data in a Statistical Project

Updated 17 October 2026 · Fact-checked

After organising survey data, choose the tool to match the question: mean for a typical value when data are symmetric, median when extreme values exist, mode for the most common value, percentages for shares, and correlation for a relationship between two variables. Interpret each result in words, link it to the objective and state limitations.

Decide what question you are asking first; that tells you which statistical tool to use on your project data.

Illustration drawn for QuestionBuddy.

Understand Analysing and Interpreting Project Data

Choosing a tool.

  • Typical value: mean (if data are fairly symmetric), median (if a few very large or small values), mode (the most common category or value).
  • Shares and comparisons: percentages and relative frequencies; pie and bar diagrams.
  • Spread: range or quartile gap.
  • Relationship between two numerical variables: scatter diagram and correlation coefficient.
  • Change over time: line graph and index numbers.

Worked analysis 1 (pocket money). Ten students' weekly pocket money (Rs): 200, 250, 300, 300, 350, 400, 450, 500, 500, 750. Sum = 4,000, so mean = 400. Ordered middle values are 350 and 400, so median = 375. Modes: 300 and 500 (bimodal). One high value (750) pulls the mean above the median; for a 'typical' student the median Rs 375 is a fairer summary. Range = 750 − 200 = 550.

Worked analysis 2 (study hours and marks). Hours studied (X): 1, 2, 2, 3, 3, 4, 5, 5, 6, 7; marks (Y): 40, 45, 50, 55, 60, 62, 70, 75, 78, 85. Computing the Pearson coefficient gives r = 0.99: a very strong positive association.

Interpreting. (1) State the number and what it measures. (2) Say what it means in plain words with units. (3) Link to the objective. (4) Mention limitations: small sample, possible bias, correlation is not causation, answers self-reported.

Writing conclusions. Answer the objectives directly; support each statement with a figure from the analysis; avoid claims beyond the sample ('in our sample of 10 students...'); give practical suggestions (for example for budgeting or study schedules).

Common errors. Using the mean for skewed data; reading causation from correlation; confusing percentage with percentage points; quoting results with more decimals than the data justify.

Presentation of results. One table or diagram per finding; label units; place interpretation beside the figure.

Flow chart: organised data → pick tool → compute → interpret in words → conclusion and limitations.

Analysing and Interpreting Project Data: key facts

Typical value
Symmetricmean
skewedmedian
most commonmode
Choice
Percentage share
Part / total x 100
Shares
Relationship
r from paired data
Between -1 and +1
Interpretation
  • Number
  • meaning
  • objective
  • limitation
Four-part comment

How to answer Analysing and Interpreting Project Data questions

Questions give small data sets and ask for the right measure and the interpretation.

  1. 1Look at the data for extreme values before choosing the average.
  2. 2Compute the measure carefully with units.
  3. 3Write a sentence interpreting it.
  4. 4Relate it to the project objective.
  5. 5State a limitation and a suggestion.

Analysing and Interpreting Project Data in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Pocket money report

Suppose a group reports the mean pocket money as Rs 400 though most students get Rs 300 to Rs 500.

Which measure should they report and why?

Try it first, then show the solutionSolution
  1. One student gets Rs 750, raising the mean.
  2. The median is Rs 375, closer to what a typical student receives.
  3. Report the median (and mention the mean) with the range.

Answer: The median Rs 375.

Memory hook: Extreme value tugs the mean.

Tricks to remember Analysing and Interpreting Project Data

Short memory aids. Say each one aloud once, then use it on a question the same day.

  • Skewed? Median

    Median for skewed data.

    Use it when: Choice

  • Say it in words

    Always interpret a number in plain words.

    Use it when: Interpretation

  • Sample only

    Limit claims to the sample.

    Use it when: Conclusion

Analysing and Interpreting Project Data: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Average choice · 4 marks · Short answerBoard level

Weekly pocket money (Rs) of 10 students: 200, 250, 300, 300, 350, 400, 450, 500, 500, 750. Find the mean, median and modes, and state which best represents a typical student.

Try it first, then show the solutionSolution
  1. Mean = 4000/10 = 400 (1 mark).
  2. Median = (350 + 400)/2 = 375 (1 mark).
  3. Modes: 300 and 500 (1 mark).
  4. Median 375 best represents the typical student because 750 raises the mean (1 mark).

Answer: Mean 400; median 375; modes 300 and 500.

Example 2: Percent share · 2 marks · Very short answerBoard level

Out of the 10 students, 4 save more than Rs 100 a week. Find the percentage and present it with a suitable diagram.

Try it first, then show the solutionSolution
  1. 4/10 x 100 = 40 per cent (1 mark).
  2. Pie diagram: 40 per cent = 144 degrees and 60 per cent = 216 degrees (1 mark).

Answer: 40 per cent; pie with 144 and 216 degrees.

Example 3: Interpreting r · 3 marks · Short answerHarder board level

For hours studied and marks of 10 students, r = 0.99. Interpret it in three sentences with a limitation.

Try it first, then show the solutionSolution
  1. r is positive and close to 1: more hours go with higher marks (1 mark).
  2. This is in our sample of 10 students (1 mark).
  3. Association does not prove that hours alone cause the marks; ability and other factors may matter (1 mark).

Answer: Strong positive; not causal; limited sample.

Example 4: Report writing · 3 marks · Short answerHarder board level

A group finds the median weekly time on screens is 18 hours and 70 per cent exceed 14 hours. Write a conclusion, a limitation and a suggestion.

Try it first, then show the solutionSolution
  1. Conclusion: students in the sample typically use screens about 18 hours a week and most exceed 14 hours (1 mark).
  2. Limitation: small, self-reported sample (1 mark).
  3. Suggestion: set a screen-time plan and repeat the survey after a month (1 mark).

Answer: Conclusion, limitation, suggestion.

Example 5: Spot the error · 5 marks · Long answerHOTS / competency

A group concluded: "Since r = 0.8 between pocket money and marks, giving more pocket money raises marks, and 40 per cent means 40 percentage points higher than last year's 30 per cent". Identify three errors and correct them.

Try it first, then show the solutionSolution
  1. Correlation is not causation: money may not raise marks (1 mark).
  2. A common factor such as family support may explain both (1 mark).
  3. From 30 to 40 per cent is a rise of 10 percentage points, not 40 (1 mark).
  4. It is a rise of 33.3 per cent in relative terms (10/30 x 100) (1 mark).
  5. Claims should be limited to the sample (1 mark).

Answer: Causation, percentage point, and generalisation errors.

Where students lose marks in Analysing and Interpreting Project Data

The slips examiners see most often, and what to write instead.

  • Mistake: Mean for skewed data

    Outlier ignored.

    Wrong working

    Always use the mean.

    Right working

    Use the median when extremes exist.

    Do this: Check outliers.

    Usually costs: 1 mark.

  • Mistake: Percentage point mix-up

    Terms confused.

    Wrong working

    30 to 40 per cent is a 40 per cent rise.

    Right working

    It is 10 percentage points (33.3 per cent relative).

    Do this: Subtract.

    Usually costs: 1 mark.

  • Mistake: No interpretation

    Numbers only.

    Wrong working

    Write the value of r only.

    Right working

    Explain it in words.

    Do this: Plain words.

    Usually costs: 1 mark.

Exam tips

  • Pick the tool to match the question.
  • Interpret every number.
  • State limitations.
  • Do not claim causation.

Practice questions on Analysing and Interpreting Project Data

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

  1. Q1 · 1 mark · MCQBoard level

    For data with a few very large values, the best typical value is the
    (a) mean (b) median (c) range (d) total

    Hint

    Resistant.

    Answer

    (b).

  2. Q2 · 1 mark · Assertion-reasonHarder board level

    Assertion (A): A project conclusion should mention limitations.
    Reason (R): Sample size and bias affect how far the results can be trusted.
    (a) Both A and R are true and R is the correct explanation of A.
    (b) Both A and R are true but R is not the correct explanation of A.
    (c) A is true but R is false.
    (d) A is false but R is true.

    Hint

    Honesty.

    Answer

    (a).

  3. Q3 · 2 marks · Very short answerBoard level

    Find the range and mean of 12, 18, 20, 25, 30, and comment.

    Hint

    Spread and centre.

    Answer

    Range = 30 - 12 = 18; mean = 105/5 = 21. The values are fairly close to the mean, so the data are not widely spread.

  4. Q4 · 4 marks · Case-basedHarder board level

    Read and answer.
    Suppose a group finds the mean daily savings are Rs 14, median Rs 10 and mode Rs 8.
    (a) Describe the shape. (1)
    (b) Which is the best measure of typical saving? (1)
    (c) Give a reason. (2)

    Hint

    Mean > median > mode.

    Answer

    (a) Positively skewed. (b) Median. (c) A few large savings pull the mean upward, so the median is nearer to the typical student.

  5. Q5 · 3 marks · Short answerHOTS / competency

    Suppose two groups collect the same data; Group A reports only the mean, Group B reports mean, median, range and a diagram. Evaluate which report is more informative.

    Hint

    Completeness.

    Answer

    Group B gives the centre, the typical value and the spread and the picture of the distribution, so it is more informative. A single mean can hide skewness and spread.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

  1. 1.Best average for skewed data?Show answer

    Median.

  2. 2.Tool for two variables?Show answer

    Correlation.

  3. 3.Range formula?Show answer

    Largest minus smallest.

  4. 4.What is bimodal?Show answer

    Two modes.

  5. 5.Percentage point?Show answer

    Difference of two percentages.

  6. 6.Conclusion should answer?Show answer

    The objectives.

Analysing and Interpreting Project Data: frequently asked questions

How do I choose an average?

By the shape of the data.

How do I interpret r?

State size, sign and meaning in words.

Why mention limitations?

To show scope.

What is bimodal?

Having two modes.

Can I claim causation?

No, not from correlation alone.