Sources, data and sociological evidence
Classify primary and secondary, qualitative and quantitative evidence, then interpret tables, charts and written accounts carefully.
Section 1.2 · Sources, data and sociological evidence
Exam scope and assessment notes
This lesson is written for Cambridge IGCSE Sociology 0495. It maps section 1.2 in the 2025–2027 Version 3 and 2028–2030 Version 1 syllabuses; Cambridge reports no significant teaching changes for 2028–2030. Use current, credible and age-appropriate examples from more than one society. Check local law and school policy before discussing sensitive or legally restricted family, marriage, crime or punishment examples. Do not ask learners to disclose personal experiences. These lessons present sociological explanations for analysis, not endorsements of political positions or stereotypes.
Before you begin
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Before you start: A researcher analyses a newly collected set of interview transcripts. Which description fits?
What you will learn
- Distinguish evidence collected first-hand from existing sources, and qualitative from quantitative data.
- Evaluate official statistics, historical and personal documents, digital sources and media content.
- Interpret sociological studies, diagrams, tables, charts and graphs without claiming more than they show.
Classify by origin and form
Primary data are gathered for the current enquiry; secondary evidence already exists. Qualitative data describe meanings or accounts; quantitative data use numbers. A new online questionnaire is primary, even though it uses the internet.
Official statistics can cover large populations but reflect the categories and recording practices used. Historical or personal documents offer context but may have selective authorship. Digital and media sources can be timely, yet may be edited, incomplete or shaped for an audience.
Read evidence before explaining it
Tables and graphs show values, groups and time periods; check labels, units, scales and denominators before comparing. A percentage and a count answer different questions.
A sociological study summary can support an explanation, but check who was studied, when, how and for what purpose. Patterns in a source can suggest an interpretation; they do not automatically reveal motives or prove a theory.
Sources for this lesson
Pause and explain
What does a rate per 1,000 residents help control when comparing two cities?
Worked example
A published table shows reported thefts per 1,000 residents in two cities. What can and cannot be concluded?
Show the worked solution
- Compare the rates only after checking the same year, definition and population denominator.
- The table can show a difference in recorded reports per resident.
- It cannot establish the true amount of theft or explain the difference without evidence about reporting and recording.
Answer The rate compares recorded reports, not necessarily all incidents or the causes of any gap.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A student uses an existing census table and conducts new interviews with residents. Classify both sources and give one limitation for each.
Give me a hint
Classify source origin separately from its format.
Compare my reasoning
- The census table is secondary evidence; check its date, definitions and collection categories.
- The interviews are primary data and may be qualitative; consider who was invited and who agreed.
- Use both only for the question they can support, and compare whether their contexts match.
The census is secondary and may be broad but can use categories that do not fit the enquiry. The interviews are primary and can explore meaning, but a small or self-selected group may not represent residents.
Look for these in your work
- Classifies both by origin
- Distinguishes format from origin
- Evaluates evidence in context
A graph shows a rise in recorded complaints after a new reporting website opens. Explain two possible interpretations.
Give me a hint
An increase in reports can reflect events, recording or willingness to report.
Compare my reasoning
- Check whether the graph uses counts or rates and whether the period and categories are consistent.
- One possibility is that the number of underlying incidents increased.
- Another is that reporting became easier or more complete; further evidence is needed to distinguish them.
The graph establishes a rise in recorded complaints under its definition. It does not alone show that incidents rose, because the new website may have changed access or recording.
Look for these in your work
- Reads the measure correctly
- Gives two plausible interpretations
- Separates recorded reports from underlying events
Choose a useful secondary source for studying how a public debate about education changed over time, and explain a check you would make before using it.
Give me a hint
Historical documents and media content can show changing language but have audiences and selection effects.
Compare my reasoning
- Select dated newspaper or broadcast archives, policy documents or public speeches relevant to the period.
- Check who produced each item, its audience, selection criteria and whether the archive preserves comparable material.
- Compare across more than one source rather than treating one publication as the whole debate.
A dated media archive or policy record could show how language and priorities changed. The researcher must consider authorship, audience, missing records and whether sources from different years can be compared fairly.
Look for these in your work
- Chooses a relevant source
- Evaluates authorship and selection
- Uses comparison without claiming completeness
Common mistakes
- Calling an online survey secondary because it is online
- Comparing totals where population sizes differ
- Treating a media post or official statistic as complete and neutral by itself
What can you explain now?
What does a rate per 1,000 residents help control when comparing two cities?
Compare with the explanation
A difference in population size
A difference in whether every incident was reported
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Classify one source by origin and form, then name one question to ask before using a chart.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.