Thicker paper and larger font increased response and completeness in a postal survey

Abstract

Objective

To investigate the effect of font size and paper thickness on the response to, and completion of, a self-completion postal questionnaire among older people with joint pain.

Study Design and Setting

Randomized trial. People aged 50 years and older with joint pain who consulted a general practitioner at one of five general practices in Central Cheshire were sent a postal questionnaire. Questionnaire format (large or small font size, thick or thin paper) was randomly allocated using a 2 × 2 factorial design.

Results

Questionnaires were received from 502 out of 650 participants (crude response 77%). Response was significantly higher for participants receiving questionnaires with a larger font size (79.3% vs. 75.2%; hazard ratio 1.26, 95% confidence interval: 1.02, 1.56). Paper thickness had no significant effect on response. Completion (measure by assessing double-page turnover error) was increased in participants receiving questionnaires printed on thicker paper (3.2% vs. 7.1%; P = 0.049) but was not affected by font size.

Conclusion

This study demonstrates that questionnaires in larger font and on thicker paper may produce higher and more complete responses than surveys using standard size font and standard thickness paper, and should therefore be considered in studies among older people.

Introduction

Self-completion postal questionnaires are commonly used in epidemiological research to collect data from participants. Maximizing the response rate is important given that nonresponse results in a loss of statistical power and increases the potential for selection bias. Researchers have identified a number of strategies that may help to improve survey response, including the use of repeated mailings, having an interesting research topic, short questionnaires, prenotification of the study, monetary and nonmonetary incentives (such as prize draw tickets), colored ink, personalized questionnaires, university endorsed research, first class post, and enclosing stamped return envelopes [1], [2], [3], [4].

A recent Cochrane review [5] included 372 trials examining various methods to increase the response to postal questionnaires. Only a minority of these trials were exclusively conducted exclusively in older people (aged 50 years and older) and details on age were rarely presented. Yet, epidemiological surveys of older people pose special challenges to researchers, which in part are attributed to the differences in health status and level of education in this age group [6].

The literature conducted in studies of older people provides only limited information on methods to increase questionnaire response. Iglesias and Torgerson [7] found in a study of women older than 70 years that a five-page questionnaire achieved a higher response than a seven-page questionnaire but that increasing the questionnaire length did not affect the quality of the answers. Iglesias et al. [8] also investigated questionnaire layout, finding that individual Short Form 12 Health Questionnaire (SF-12) items were better completed than the traditional “stem and leaf” format. Shah et al. [9] found that asking an income question or seeking consent to access medical records did not reduce response rate in a study of patients aged 65–74 years and Beebe et al. [10] found that a combination of white paper and small-size questionnaire increased response in people older than 50 years. Puffer et al. [11] recommended using double- rather than single-sided questionnaires and using single rather than multiple booklet designs for studies of older people and Taylor et al. [12] found a small increase in response in older people when colored ink was used instead of black ink. In a study of older people with osteoarthritis, Rat et al. [13] found that the order of question had only a minimal effect on the quality of responses. Furthermore, self-completion postal questionnaires have been demonstrated to produce higher levels of response in older people than face-to-face interview but may result in higher levels of missing data [14]. Although high response is important to minimize the risk of bias, the completeness of data collected should also be considered [15].

Two factors that may influence the response and completeness of self-report postal questionnaires in older people are the questionnaire font size and the thickness of the paper. A questionnaire written using a larger font is likely to be easier to read and complete by those with poor vision than those written with smaller font sizes. It is also possible that questionnaires produced using thicker paper would be easier to page turn for participants with hand problems, such as osteoarthritis which is both highly prevalent and disabling in older populations [16]. Easier to turn pages could result in a reduced rate of “double-page turnover” (defined as complete missing data on two facing pages when the questionnaire was otherwise successfully completed). To our knowledge, the effect of these factors on survey response has not been investigated, and they have been identified as research priorities by a Cochrane review examining methods to increase the response rate to postal questionnaires [5].

We present the results of a study investigating the effect of differing font size and paper thickness on the response rate and level of completion of postal questionnaires in older people.