Naturalistic Driving Study: Technical Coordination and Quality Control (2014)

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68 C h a p t e r 5 The use of hand-held mobile devices (e.g., cell/smart phones) has skyrocketed in recent years, transforming our world in many ways. Corresponding to this increase, the impact on safety associated with the use of such tech- nologies while driving has been the focus of much research discussion and advocacy efforts. The SHRP 2 NDS data set presents a unique opportunity to study this topic in an envi- ronment in which real-world, safety-related events can be observed in the context of associated metrics of usage and exposure. To this end, the Cell Phone Records Study (CPRS) was commissioned as the first follow-on to the SHRP 2 NDS. This study was conceived as a follow-on study because the provi- sion of cell phone records was not included in the original informed consent forms signed by participants. Therefore, participants had to agree to be contacted for future studies before they could be approached about participating in the CPRS. Those who did agree to be contacted were handed participation packets by site contractor staff as they exited the driving study. Those who granted consent were asked to provide access to specific aspects of their calling and texting records for the duration of their participation in the driv- ing study. In this way, the driving and cell phone records can be more easily matched based on universal time syncs, indicating—with video verification—which trip files are accompanied by the simultaneous use of cell phones. To be eligible for the CPRS, participants had to be 18 years old or older, be able to access a minimum of 3 months of their cell phone records overlapping their participation in the driving study, and if not the authorized account holder of the wire- less account, they had to be able to obtain permission from the authorized account holder to release the records. Use of minors in a study requires parental consent in addition to the minor’s assent, both of which typically must be given in person to ensure freedom from parental coercion. The CPRS design called for consent to be provided remotely via mail. Therefore, including minors in the CPRS was deemed infea- sible. However, younger participants who expressed a will- ingness to be contacted regarding participation in follow-on studies were invited to participate once they reached the age of consent. Those who had prepaid cell phones, borrowed cell phones, or cell phones issued by their employer were not eligible. No minimum cell phone usage volume was specified to qualify. The two market-leading cell phone vendors, Verizon and AT&T Inc., provided authorized data for primary partici- pants to the Coordination Contractor electronically. Pri- mary participants with other providers and all secondary participants were invited to provide their own cell phone records, which were manually converted to the canonical format by Coordination Contractor personnel. Primary participants with Verizon or AT&T were compensated based on the amount of cell phone records authorized for release that overlapped with their driving records: 3–5 months of records were compensated $50. Those that provided 6 months of records or more were compensated $100. Par- ticipants who provided their own data were compensated based on the number of months of data they could provide that overlapped with their time in the study. For these indi- viduals, compensation was provided at the rate of $10 per month for call records and an additional $10 a month for text records. The data being collected include the date, time, and dura- tion of calls; origin of the call (participant or other); and the date, time, and origin of text messages (including picture or video messages, as available). It is also important to note which aspects of the cell phone records were not collected as data. Neither call nor text message content was recorded or collected. In addition, the phone number of the other party was not collected, and no identifying information of any kind was collected. That is, cell phone data were associated with participant records via participant ID only. Cell Phone Records Integration Study

69 Thus, the amount of data collected from each indi- vidual varied based on a variety of factors, including the following: • Duration of participation in study with overlapping cell phone use (a range of 24+ to 3 months); • How much data could be accessed based on the estimated retention periods noted in Table 5.1; • Whether or not text, picture, or video messages were included in each month of data; and • The participant’s ability to generate the data (i.e., those for whom a direct feed from the provider was not available as specified above). Figure 5.1 shows the distribution of participants (as of January 16, 2014) by age range of participation in the NDS who consented to participate in the cellular phone records follow-on study. Table 5.1. Data Retention Periods for Major Cell Phone Service Providers (as of Jan. 16, 2014) Provider Maximum Data Retention (months) Records ObtainedCall Data Text Verizon 12 12 243 AT&T 24 24 67 Participant provided Varies Varies 70 Total — — 380 Figure 5.1. Age range and gender of cell phone study participants. It is important to note that cell phone records are not indefinitely accessible. That is, each provider maintains such data for different durations, as indicated in Table 5.1. The number of cellular phone records collected of January 16, 2014, is also recorded in Table 5.1.