Self-selection monetary incentives change daily travel behaviour: a field experiment on Beijing subways

1. Control group: Participants receive irrelevant information every week;
2. Information feedback group: Participants receive feedback on their travel behaviour from the previous week every week, without any additional monetary reward;
3. Multiple-times self-selection group: During the experiment, participants receive information feedback every week and can choose their own monetary reward mode for the week;
(1)Piece rate: Participants receive a 5 yuan reward for each early peak period travel. They can earn the reward once per day at most. A maximum of three rewards can be obtained per week.
(2)All or nothing: Participants who travel during the early peak period on at least three days in a week can directly receive a reward of 15 yuan;
4. One-time self-selection group: Before the first reward week, participants choose their reward mode for the entire experiment period as either a piece rate or an all-or-nothing reward. Once chosen, it cannot be changed.

2023-12-16

2024-02-10

(1)Departure time of daily morning commuting travel--during the experiment
(2)Departure time of daily morning commuting travel--after the end of the experiment, in long term
(3)Choice of peak avoidance--during the experiment
(4)Choice of peak-avoidance---after the end of the experiment, in long term

All subjects in our experiment us smart cards to pay subway fares. Before boarding a station, they swipe the card at the station of origin to open the gates. Distance-dependent fares are automatically collected when they again swipe the card before exiting the destination station. For each subway ride, the smart card records the origin, destination, start and finish times, and fare. This fare-collection system greatly facilitated the implementation of our experiment and minimized measurement error in the data.
By analysing the smart card data of subjects during the historical period, the experimental period, and the post-experimental period, we can observe the time at which travellers enter the subway station for their morning commute each day. By comparing the travel patterns during the experimental period with those of the historical period, we can observe whether travellers have chosen peak avoidance. After the incentive period ends, by continuing to monitor the travelers' travel patterns, we can observe whether their off-peak travel behaviour persists in the long term.

We will recruit subway commuters for the experiment. Recording their card numbers and tracking their travel behaviour over time. During the treatment period, subjects will be incentivized by information feedback and 2 kinds of monetary incentives. We continued to track their behaviour for 2-4 months after the experiment ended.

Experiment design:
(1) Event theme: Beijing Subway Green Low-Carbon Travel Challenge Month
(2) Event duration:
① A total of 2 months, with weekly cycles;
② After the two-month event, continue to observe passenger behavior for 2-4 months.
(3) Event area: Jinggang Subway Line 4 to Daxing Line (high passenger flow, significant peak-hour tidal flow). Plan to recruit participants from 5 stations: Majiabao, Xingong, Gaomidian North, Gaomidian South, Zao Yuan.
(4) Target travellers:
① Selection criteria:
- After recruitment, extract the user's past 3 weeks of historical data. The user should have used Line 4 for commuting during the early peak period at least 3 times in 1 week, 5 times in 2 weeks, and 7 times in 3 weeks.
- Travelers who do not plan to leave Beijing in the next 2 months.
② Number of participants: Recruit about 440 eligible participants, divided into 4 groups.
③ Recruitment method:
- Promotional materials: designed by Beijing Jiaotong University, including publicity canvas, event public account, registration questionnaire, QR code for registration, and registration link;
- On-site promotion: set up a publicity area in the selected subway station hall/entrance, post a poster or place a roll-up banner, and have staff on-site for promotion and recruitment, avoiding the passenger flow line.
All on-site staff are students from Beijing Jiaotong University, 1-2 students per station, wearing student identification on-site.
(5)Treatment groups
① Control group: Participants receive irrelevant information every week;
② Information feedback group: Participants receive feedback on their travel behaviour from the previous week every week, without any additional monetary reward;
③ Multiple-times self-selection group: During the experiment, participants receive information feedback every week and can choose their own monetary reward mode for the week;
(1)Piece rate: Participants receive a 5 yuan reward for each early peak period travel. They can earn the reward once per day at most. A maximum of three rewards can be obtained per week.
(2)All or nothing: Participants who travel during the early peak period on at least three days in a week can directly receive a reward of 15 yuan;
④ One-time self-selection group: Before the first reward week, participants choose their reward mode for the entire experiment period as either a piece rate or a all or nothing reward. Once chosen, it cannot be changed.

Not available

Stratified randomization by stata

individual

No

440 individuals

440 individuals

110Control group
110Information feedback group
110Multiple-times self-selection group
110One-time self-selection group

Unit of measurement: change of probability of choosing peak avoidance. For an error probability of alpha = 0.05, a power of 1- k = 0.95, and the standardized minimum detectable effect size is 0.5, N =105 per treatment group.