How do I label a chart so people can understand what its survey percentages mean?
Quick answer
State who or what each percentage is calculated from, whether people could choose one answer or several, and how unanswered questions are handled. Put the base—such as “among 120 respondents who answered this question”—near the chart, not only in a distant note. If the base differs by question or you exclude unanswered responses, say so. Use a short caption that spells out those choices.
The question, the details, the next step.
My survey chart shows percentages, but a reader might not know what they are percentages of. What should I label?
Put the denominator—the group counted for each percentage—where readers can see it alongside the chart. “Among respondents” may be too vague if some people skipped that question. Give the count and identify whether it includes everyone invited, everyone who took the survey, or only those who answered that item.
For example, suppose a hypothetical survey has 150 participants, but only 120 answer a question. If the chart uses those 120 answers as its base, label it: “Base: 120 respondents who answered this question.” If instead the percentages use all 150 participants, say that. The count and wording should match the calculation you actually used; don’t infer a base from the bars.
Does the fact that people could pick more than one option change the label?
Yes. State whether the question allowed one answer or multiple answers, because that changes how a reader should interpret the percentages. For a single-choice question, you might say “one answer per respondent.” For a select-all-that-apply question, say “multiple answers allowed” or “respondents could select more than one option.”
A useful check is whether the displayed percentages are intended to add up to 100%. Don’t imply they must do so if respondents could choose multiple options. Instead, explain the response basis in the caption. For example: “Percentages show the share of respondents who selected each option; multiple selections were allowed.” Use that wording only if it describes your survey and calculation.
What should I say about people who left the question blank?
Say whether unanswered questions are excluded from the percentage base or included in it, and give the number of answers used if you can. If blank responses are excluded, a reader should not have to guess that from a denominator that differs from the total number of participants.
Hypothetical example: 150 people took a survey, 120 answered a particular item, and the chart calculates percentages from those 120 answers. A clear note is: “Base: 120 people who answered; 30 did not answer and are not included in these percentages.” If blanks are included in your calculation, describe that accurately instead. If you have not checked how the chart was calculated, verify the base before writing the caption rather than assuming how missing answers were treated.
Can you give me a caption template that brings those details together without making the chart label too long?
Use a short chart title for the subject, then a caption or note for the calculation details. Adapt this copyable template:
“[Chart subject]. Percentages are of [number and description of people or answers in the base]. [One answer per respondent / Multiple answers allowed]. [Unanswered responses are excluded / Unanswered responses are included].”
For a hypothetical select-all question, it could read: “Ways participants prefer to receive updates. Percentages are of the 120 respondents who answered this question. Multiple answers allowed. The 30 participants who left it blank are not included.” Replace every bracketed detail with what your survey actually did. If the base varies between questions in the chart, clarify which base applies to each one; don’t use a single shared note if it would leave readers uncertain.
A practical checklist
Name the exact group or set of answers used as the percentage denominator.
Include the base count and say whether it refers to participants, question answers, or another clearly defined group.
State whether respondents could choose one answer or multiple answers.
Describe whether blank or unanswered questions are included in the calculation.
Check that the caption matches the chart’s actual calculation and any changing bases.
A few more useful answers
Should I put the denominator in the chart title?
Use the title for the chart’s subject and put the denominator in a nearby caption, subtitle, or note. The key is that readers can connect the base to the percentages without searching elsewhere.
What if I don’t know how unanswered questions were handled?
Check the survey data or calculation before publishing the label. Until you know the base, avoid stating that blanks were included or excluded.
Do I need to show both a count and a percentage?
Showing the percentage base count helps readers understand what the percentage represents. Whether to show counts for each answer option as well depends on what helps readers interpret your particular chart.