Learn in your language
Skip to content
A Level · Cambridge (CIE) · 9990

Present and interpret psychological data

Choose and interpret the syllabus data displays and descriptive summaries without adding calculations or statistical tests that are not required.

Cambridge International AS & A Level Psychology 9990 · 2028–2030 · Version 1 · MC-DATA-ANALYSIS

Original StudyForA teaching mapped to the Cambridge 2028–2030 syllabus. These lessons are independent study support, not Cambridge material, official mark schemes or awarded grades. No lesson reproduces a research article or Cambridge question.

Before you begin

  • This pathway supports the 2028–2030 syllabus only. AS candidates take Papers 1 and 2; A Level candidates also study two of the four specialist options and take Papers 3 and 4. The separate 2027 syllabus is not mapped here.

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

Which display is used for paired scores on two measured variables?

What you will learn

  • Present and read a data table
  • Interpret mode, median, mean, range and standard deviation conceptually
  • Select and interpret bar charts, histograms and scatter graphs
  • Stay within the specified no-calculation scope

Tables organise what was measured

A clear table labels each variable, category and unit and makes the comparison visible. Check that totals and group labels match the scenario. Tables can show exact values; graphs help readers see distributions or patterns. Do not infer a pattern that the displayed values do not support.

Central tendency and spread describe different features

Mode is the most frequent value or category. Median is the middle value when ordered; mean is the arithmetic average. The syllabus requires recognising and knowing what these measures are, but says no median or mean calculation is necessary. Range describes the span from minimum to maximum. Standard deviation describes spread around a mean; a larger standard deviation means scores are more dispersed, not that the mean is larger.

A measure can hide distribution shape or unusual values. Interpret the display and context together; do not claim a group differs meaningfully from a single summary alone.

Choose the display for the variable structure

A bar chart compares separate categories and uses gaps between bars. A histogram displays frequencies for continuous intervals, with adjacent bars; unequal class widths require attention to density if area represents frequency. A scatter graph plots paired values for two measured co-variables and can show direction, form, strength and possible unusual points. A scatter pattern is associational, not causal evidence.

Label axes, categories, units and intervals clearly. To amend a display, preserve the values, axis scale and boundaries. Never change a graph scale to exaggerate a difference or imply values that were not recorded.

Sources for this lesson

Pause and explain

Which statement about a histogram is accurate?

Put the idea to work

Worked example

A table compares the number of helping actions in two groups. One group has a higher mean but also a larger standard deviation. What does each summary tell you?

Show the worked solution
  1. The mean describes the group’s average score.
  2. The larger standard deviation indicates greater spread around that group mean.
  3. The summaries alone do not show whether the groups differ reliably or why.

Answer One group has the higher average, while its scores are more dispersed; no causal or significance claim follows from those summaries alone.

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.

1 · Guided

Scores are 2, 3, 3, 5, 7. Identify the mode and explain what a reported range of 5 represents, without calculating summary measures.

Give me a hint

Mode is the most frequent value; range describes the span from minimum to maximum.

Compare my reasoning
  1. The value 3 appears most often, so it is the mode.
  2. The lowest score is 2 and the highest is 7.
  3. A reported range of 5 describes the distance between those endpoints; no further statistic needs to be calculated.

Mode = 3; a range of 5 means the scores span five points from the lowest to highest value.

Look for these in your work

  • Mode found
  • Endpoints interpreted
  • No unnecessary calculation
2 · Independent

A researcher groups reaction times into adjacent intervals and displays each interval's frequency. Which graph is appropriate, and what should the axes show?

Give me a hint

Reaction time is continuous and grouped into intervals.

Compare my reasoning
  1. Use a histogram.
  2. The horizontal axis should show reaction-time intervals and units.
  3. The vertical axis should show frequency; adjacent bars represent neighbouring intervals.

A histogram with reaction-time intervals on the x-axis and frequency on the y-axis; bars touch because the intervals are continuous.

Look for these in your work

  • Graph type matches variable
  • Axes and units identified
  • Bar adjacency explained
3 · Transfer

A report shows a positive scatter pattern between hours spent practising and self-rated confidence. Write a careful interpretation and one limitation.

Give me a hint

Describe measured association without claiming an intervention effect.

Compare my reasoning
  1. Higher practice-hour values tend to accompany higher confidence ratings.
  2. The pattern is positive; its strength depends on how closely points follow a trend.
  3. The graph alone cannot show that practice caused confidence; prior confidence or access to resources may affect both.

The measured variables show a positive association, but the scatter graph cannot establish causation; a third variable may influence both.

Look for these in your work

  • Direction described
  • Strength not invented
  • Causal limitation stated

Common mistakes

  • Using bar-chart bars that touch for separate categories or gaps in a histogram of continuous intervals.
  • Saying standard deviation is the average score; it describes spread.
  • Assuming two means alone show a meaningful or statistically significant difference.
  • Calculating statistics or tests beyond the syllabus requirement.
Recall without your notes

What can you explain now?

What does a larger standard deviation usually indicate?

Compare with the explanation

Scores are more spread out around the mean.

It describes variability, not the size of the average.

After trying it yourself, choose your next review. This is your self-assessment.

Your review choice appears on Today. Sign in to sync it across devices.

Make it stick

Which summary describes the most common value, which describes spread, and which graph fits categories, continuous intervals or paired measurements?

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.

Keep learning Psychology

Course scope and assessment

Seven original lessons map all 15 AS research-method and methodological-concept sections to explained Guided, Independent and Transfer practice. All 12 compulsory AS core studies have original study-specific teaching and staged practice; five additional A Level methodology lessons cover research design and validity. All 15 Clinical, all 15 Consumer (2.1.1–2.5.3) and all 15 Health (3.1.1–3.5.3) Psychology sections link to original teaching and staged practice. All 15 Organisational Psychology sections 4.1–4.5 now have original teaching and explained staged practice; the six new 4.4–4.5 lessons bring the planning map to 92 of 92 indexed sections. Consumer lessons cover physical and psychological environments; decision models, heuristics and mistakes; packaging, selling and buying; advertising, self-monitoring, product placement, brand recognition and slogans. Evaluation boundaries are explicit: studies use particular products, samples, tasks and settings; gaze, recall, self-report, EEG indices, ratings, choices and purchases are different outcomes. Health evidence is bounded: Laba et al. measured hypothetical preferences; Riekert and Drotar raise a non-response concern; Chung and Naya's cap tracked openings, not swallowing; Chaney et al. was a short caregiver-reported pilot; Yokley and Glenwick examined immunisation attendance in one public-health setting. MacLachlan et al. report one patient, not a controlled treatment effect; Brudvik et al. compared separate child, parent and physician ratings in one emergency department. Chandola et al. found a cohort association; Wang et al. measured responses during a monitored arithmetic task; Evans and Wener observed commuters; Bridge et al. found mixed self-rated outcomes in radiotherapy. Janis and Feshbach measured short-term self-reports in one school; Lewin et al. tested a rehabilitation package, not information alone. Tapper et al. and Fox et al. studied bounded school and worksite programmes; incentive effects do not establish transfer or rule out reporting effects. Weinstein measured comparative expectations, while Seligman’s framework is conceptual and Shoshani and Steinmetz used a school-level comparison. These findings do not establish universal health effects or diagnose individuals. Need-theory examples use a child measurement study, not a workplace test; SMART is a practical checklist, not a motivational theory. Landry et al. compared reward framing with student volunteers in a lab; this does not establish universal effects in workplaces. Cuadrado et al. (2008) measured undergraduate evaluations of presented leaders, not workplace performance or hiring; this does not establish a universal gender effect. The historical 1995 Munchausen criteria are not a current diagnostic checklist. Cambridge’s 2028–2030 Reference List treats Oruč et al. (1997) as an example of genetic explanation although its participants had bipolar I; gambling disorder is listed in Cambridge’s Clinical topic but classified under addictive behaviours in ICD-11. Candidates choose two options, but all four remain listed so schools can select a route. The 92-section count is a planning index, not a Cambridge score. Remaining work is deeper coverage review, separate-year syllabus reconciliation, timed-paper practice and human subject-expert review. The separate 2027 and 2024–2026 syllabuses are not reconciled into this route. Practice is not official grading, a timed-paper simulation or human subject-expert review.

StudyForA · Learn with understanding

Original teaching content and links to official sources. Check your exam year and qualification before using a resource.