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A matrix question is broadly defined as any question that has more than one column of response options. This requires respondents to read and provide an answer for each option, rather than just select the options that apply. Matrix questions are often more convenient for designers as they take up less space. However, they can be difficult for respondents and create a larger amount of burden. Matrix questions also tend to increase item non-response.

Matrix questions

Preferably, ask individual questions rather than using a matrix format. If a matrix question must be asked, every effort must be made to make the matrix as simple as possible to understand and complete.

Matrix questions using mark responses usually incorporate some form of underlying scale. This may be as simple as having yes / no options, or more complex such as scales asking whether respondents agree / disagree with each statement.

Format the matrix question in the same way as all other questions (ie questions in plain font, instructions first, same font size as other questions, 'note / include' boxes aligned with the question).

Example of matrix questions

Image, Example of matrix questions.  

Matrix response options

Use the same type of response option for all the response options in a matrix, for example all mark ovals or all numeric responses. The only exception is when a respondent has a choice of the response type (eg dollar response or percentage response). In this situation, it is important to consider each row at a time, and use a matrix format.

Use a table format if different types of response options are required. See section 12 for information about tables.

If mark ovals are used, the instructions for matrix questions should either be 'mark one oval for each item listed' or 'mark all that apply for each item listed'. This is dependent on how many options respondents are able to select in each row. See the example in section 11.1 for an illustration of this. top

Matrix columns

Column headings

Place column headings in the same pane as the question.

Use lower-case, plain font text, and centre over the column it relates to.

Align column headings that need to be wrapped onto two lines with the last word at the bottom of the box (closest to the response boxes) and other words stretching upwards. This makes it easier to identify which column each heading belongs with.

Example of column headings that are wrapped onto two lines

Image, Example of column headings that are wrapped onto two lines.  top

Headings should be short and use terms that are easy to interpret and understand. There is often limited space for column headings, so if they are complex, or require definitions and explanations, they are more likely to confuse respondents or be misinterpreted.

Number of columns

The number of columns is often dictated by the amount of available space, however there are also some restrictions in column numbers which stem from the use of scales.

Column spacing

Use equal spacing between each response option that is part of the main scale.

Use unequal spacing when there is a need for a 'not applicable', 'don't know', or 'no opinion' column. These items should always be on the right of all other columns ('not applicable' should always be at the extreme right). A larger gap should be added between these columns and the remainder of the options. This separation makes it more visually obvious that these options are not part of the main scale, and reduces the likelihood that respondents will just select the oval which visually looks to be the centre of the scale, rather than read the headings.

Provide sufficient space within the matrix so that the question does not look too crowded or complex.

  • At least 5mm between columns.
  • At least 4mm space between the right margin of option text, and the first response columns.

If it is necessary to spread the matrix across more than one page, there should be no other questions on the same page and all columns and rows should line up across the page. Column headings and alternate colours should also be consistent across the pages.

Example of unequal spacing

Image, Example of unequal spacing.

Multiple concepts

If each column is asking for an answer to a different concept, it is very complex for respondents to correctly interpret. Every attempt should be made to have the information set out as separate questions. top


Use lower-case plain font text for row headings, and vertically align with the question.

Place answer spaces on the right of the response options.

Align answer spaces with the centre of the row headings, even if a row heading is wrapped onto more than one line.

Use a visual cue to lead the eye from response categories on the left to the correct answer spaces on the right. Use shaded stripes for this in matrix questions, see section 8.8 for more information. Shaded stripes also identify the rows as single items, thus helping respondents to consider each row separately.

Example of a matrix row heading that is wrapped onto more than one line

Image, Example of a matrix row heading that is wrapped onto more than one line.

Use of answer codes in matrices

Do not ask respondents to answer using codes (eg an answer code would be 'Write Y for 'yes' and N for 'no''). Respondents are unlikely to read the instructions for answer codes unless they are in an obvious location. If they do not read the instructions, they may respond in ways that will be difficult to interpret. Even if they do read the instructions, they can still misinterpret them (especially for complex codes).

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