Case study: The effect of text message reminder on survey nonresponse Oona Pentala-Nikulainen 1.12.2018

outline Background Introduction Methods Results Future steps Did the text reminder activate respondents? How many respondents did we gain? What kind of respondents did it activate? Future steps 1.12.2018

BACKGROUND Nonresponse has increased especially in certain groups Sending similar reminders will increase the overall response rate but might not decrease the differences between the respondents and nonrespondents (e.g. Elliott & Hannaford 2003, Christensen et al 2015) When applying adaptive or responsive data collection designs (e.g. Lundquist & Särndal 2013) to mixed mode (postal and web) survey we also need new ways to contact the nonrespondents 1.12.2018 Nonresponse has increased especially in certain groups: We know this from the previous rounds or we can identify those groups during the data collection Sending similar reminders will increase the overall response rate but might not decrease the differences between the respondents and nonrespondents (e.g. Elliott & Hannaford 2003, Christensen et al 2015) We are interested in applying adaptive data collection methods in the later rounds so we need to find out new ways to contact the respondents.

Introduction The National FinSote Survey is a study of health, well-being and service use among Finnish adult population The sample size was 59 400 of adults 20 years old and upwards The final response rate was 46% Information was collected by mail and online questionnaire. 1.12.2018 The final response rate was 46% with big differences between different age groups; 20-to-54-year-olds 28%, 55-to-74-year-olds 58% and 75 years and older 57% (Pentala-Nikulainen et al., 2018).

Methods Hi! You received an invitation to take part in FinSote Survey earlier by mail. Please respond at www.thl.fi/finsote/answer. Your respondent code is xxxx. You will receive the password in a separate message. We tested sending a reminder via text message to a test group of 7991 20-to-54- year old nonrespondents The control group consisted of 9585 20-to- 54-year old nonrespondents for whom it was not possible to obtain an up-to-date mobile phone number The text messages were sent by programmed interface Your password concerning FinSote Survey is xxxx. Thank You in advance! More information at www.finsote.fi or p. 0800 97730. Please do not respond to this text 1.12.2018 The text reminder was an extra contact between the second and the third contact time approximately 4 months after the first contact. The reasons for the phone number not being available were usually the use of pre-paid subscriptions or having a mobile phone subscription under a new address or different name. The test group and the control group differed very little age and gender wise; in the test group there were slightly more older nonrespondents than in the control group.

REsults Men Control group 8.1% Test group 11.2% Women 1.12.2018 the effect was statistically significant only in some age groups, 25-to-29-year-olds and 45-to-49-year olds (figure 1 and table 1). There was also a difference between genders; the effect of text reminder was significant only among men (table 1).

REsults 1.12.2018 the effect was statistically significant only in some age groups, 25-to-29-year-olds and 45-to-49-year olds (figure 1 and table 1). In the test group the response rate by age group tends to be closer to the distribution of the final response rate

REsults The text messages did not result in higher number of contacts or refusals Overall we gained 299 answer between the time of sending the reminders and sending the final reminder via post After sending the text reminder and the final reminder via post we gained altogether 1044 answers from the test group and 1020 answers from the control group 1.12.2018

discussion Because the text reminder worked among certain age groups and among men we may have got a better balanced response set with sending text reminders We estimate that the text reminder brought us about 170 participants who would have otherwise been nonrespondents However the text reminder might not have been effective enough and more action should be taken in activating these participants A monitoring system and a programmed interface are needed 1.12.2018

Future steps To send text reminders earlier on during the data collection or even replace one mail reminder with text reminder To send multiple text reminders To study closer the test and control group respondents with more register data Try sending the text reminder to older agegroups 1.12.2018

REferences Elliott AM and Hannaford PC. Third mailings in epidemiological studies: are they really necessary? Family Practice 2003 Oct;20(5):592-4. Christensen AI, Ekholm O, Kristensen PL, Larsen FB, Vinding AL, Glümer C, Juel K. The effect of multiple reminders on response patterns in a Danish health survey. Eur J Public Health. 2015 Feb;25(1):156-61. doi: 10.1093/eurpub/cku057 Peter Lundquist and Carl-Erik Särndal. Aspects of Responsive Design with Applications to the Swedish Living Conditions Survey. Journal of Official Statistics, Vol. 29, No. 4, 2013, pp. 557–582, http://dx.doi.org/10.2478/jos- 2013-0040 Pentala-Nikulainen O, Koskela T, Parikka S, Kilpeläinen H, Koskenniemi T, Aalto A-M, Muuri A, Koskinen S & Lounamaa A. (2018). The basic results and methods of the National FinSote Survey 2017-2018. Internet publication https://thl.fi/en/web/thlfi-en/research-and-expertwork/population-studies/national-finsote-survey Thank You 1.12.2018