The effect of lifestyle on some non-communicable diseases: Students should be able to translate information between graphical and numerical forms; and extract and interpret information from charts, graphs and tables in terms of risk factors.

The idea

Risk-factor data often appear as tables, bar charts, line graphs or scatter graphs. Translating between forms means reading a value from a graph and writing it as a number, or plotting table values as a graph. To extract information, locate the correct axis, read the scale carefully and identify the group or category. To interpret, describe the pattern: as one variable increases, does disease risk rise, fall or stay the same? For example, a graph of daily cigarettes against lung-cancer rate may show a positive correlation. You should quote figures from the graph, compare groups and state whether the evidence supports a link. Always check units, axis labels and whether the scale starts at zero.

What earns the marks

• Reads values accurately from axes, keys and scales in tables, charts and graphs.
• Plots or completes a graph from numerical data using correct labels, units and scale.
• Describes trends or patterns, such as positive or negative correlation, between a risk factor and disease.
• Compares data for different groups, quoting numerical values to support the comparison.
• Interprets whether the data support a link between the risk factor and the disease, while noting limitations.

Common mistakes and how to put them right

• Misreading a non-zero axis start as zero.

  Put it right by checking the scale and labelling the first tick.

• Describing a trend without quoting data.

  Put it right by adding a specific value or range from the graph.

• Mixing up axes or groups.

  Put it right by naming the axis and the category before giving a value.

Exam tips

• Quote numbers with units when describing a pattern, for example 'risk rises from 5 to 20 per 1000 people'.
• Use comparative language such as 'higher than', 'lower than' or 'increases as' rather than vague words like 'different'.
• Check whether the question asks you to read a value, describe a trend or evaluate a conclusion, and answer that specific command.