How to Answer Data Analysis Questions in IGCSE Physics

Use this guide to handle data analysis questions confidently in Cambridge IGCSE Physics 0625 exams.

What data analysis questions look like

These questions give you a table of experimental results, a graph, or both, and ask you to:

• Describe the pattern or relationship.
• Use the data to calculate a quantity.
• Identify anomalous results.
• Draw or complete a graph.
• State a conclusion.

Step 1: Read the table carefully

• Identify the independent variable (what was changed) and the dependent variable (what was measured).
• Check the units in the column headers.
• Look for any obviously anomalous readings (one value that does not fit the trend).

Step 2: Describe the pattern

Use precise language:

Do not use “directly proportional” unless the data genuinely passes through the origin on a straight-line graph.

Step 3: Calculate from the data

When a question asks you to calculate using data from the table:

1. Identify which values to use (the question usually specifies a row or asks for an average).
2. Write the formula.
3. Substitute the values from the table, including units.
4. Calculate and state the answer with units.

Calculating a gradient from a graph

• Choose two points far apart on the line (not data points if possible; use the line of best fit).
• Gradient = change in y / change in x.
• Include units: if y is in metres and x is in seconds, the gradient has units m/s.

Step 4: Identify anomalous results

An anomalous result is one that does not fit the general trend. To identify it:

• Plot the data mentally or on the graph.
• The point furthest from the line of best fit is the anomaly.
• State which reading is anomalous and suggest a possible cause (e.g. “a measurement error” or “the instrument was not reset”).

Step 5: State a conclusion

A conclusion links the data to the physics:

• “The results show that resistance increases with temperature for a filament lamp.”
• “The data confirms that the extension is proportional to the applied force, consistent with Hooke’s Law.”

Keep conclusions specific. Do not write “the experiment was successful.”

Common mistakes

• Reading the wrong row from a table.
• Using data points instead of the line of best fit for gradient calculations.
• Confusing “proportional” with “increases with” (proportional requires a straight line through the origin).
• Forgetting to include the unit in a calculated answer.