**2. Methods**

## **2.1 Data collection**

Participants were recruited through Amazon Mechanical Turk to take a survey hosted on Qualtrics from January 5th to February 7th, 2022. They were required to be between the ages of 18 and 99 years old, live in the United States of America, and be the parent of at least one child above the age of thirteen to participate in the study. Compensation was provided (4 USD per valid, complete response). This research was approved by the author's university Institutional Review Board.

Of the initial 315 responses, 38 participants were removed due to not meeting the participant criteria or declining to participate at the informed consent stage of the questionnaire. An additional 50 responses were removed due to failure of attention checks such as "What is the current month?" or "Please respond no to this question." Lastly, a final 34 participants were removed due to responding to the survey questions for a child that was not within the acceptable age range of 13–19 years old. A total of 191 valid responses were used for the analysis.

### **2.2 Questionnaire development**

#### *2.2.1 Parent demographics*

Before beginning the demographic section, participants were asked to confirm that they met the criteria to participate and agree to the terms laid out by an electronic informed consent form. Then, participants were asked to first answer a set of demographic questions regarding themselves. Parent demographic questions included age, sex, gender, ethnicity, and education level. Participants were also asked if they held a valid driver's license, which state this license was issued in, how many years of driving experience the participant had, and how many accidents they have caused. These questions were asked to gather information regarding the participants' driving experience.

#### *2.2.2 Early adopters and autonomous vehicle opinions*

Participants were next asked to answer a set of questions regarding their general opinions about AVs. Willingness to adopt new technologies plays a role in opinions of AVs, as it is a relatively new innovation [23]. Parents were given a description of an early adopter of technology and then were asked if they considered themselves to be an early adopter. A description of AVs was given to define and frame the concept for the duration of the study [28]. Participants were then asked how familiar they were with AVs, how useful they found them, how safe they felt AVs were, and how likely they were to ride in one. Lastly, they were asked how likely they would be to purchase an AV if cost was no issue. The phrasing of this question aims to understand which participants would be inclined to purchase an AV if the issue of cost was removed, as this is one of the larger barriers to adoption [29].

### *2.2.3 Teenager demographics*

Parents were asked to answer the next section with information regarding their teenager. If the parent had more than one teenager, they were instructed to choose one to answer the questions for. Information was then collected regarding the demographics of the teenager such as sex, gender, ethnicity, and age. It was then asked what type of license this child had, if they held one and which state this was issued in. Years of driving experience and number of accidents were asked as well. Parents were then asked to subjectively rate their child's driving performance on a 5-point scale ranging from "far below average" to "far above average."

Having an older child who is able to drive has the potential to help increase the ability to meet a family's mobility needs. For this reason, parents were also asked if their child's ability to drive is helpful for meeting the family's transportation needs. Additionally, the number of vehicles a family has is relative to the number of drivers in the household with some families having as many vehicles as drivers [30]. Therefore, it was asked if the child has a designated vehicle to use when driving or if they would be using a car that would otherwise be used by the parent. In the case of the latter option, this indicates a potential need for more options for mobility within the family. Lastly, the parent was asked to rate how often their child needed

transportation to various activities per week, regardless of how this transportation is achieved, Activities including school, work, extracurriculars, and others were rated on a 5-point scale ranging from "Never" to "5+ times a week".
