Experimental Design Details
We conduct a three-stage assignment procedure. First, the partner bank provides us with data on more than 153,000 clients. The sample represents all of the bank’s clients above the age of 40 who have their own bank account and are not excluded for ethical reasons (i.e., not legally competent). Then, we select a sub-sample of more than 27,000 clients who are eligible for our experiment (based on age, recent internet banking use, place of residence, account activity, privacy and data use settings). We will be able to contact roughly half of the 27,000 clients by letter and half by e-mail. At all stages of the study, phone calls are used as an (additional) communication channel. Second, of the 27,000 clients, we assign approximately 4,000 clients to the silent control group (ca. 700 from the e-mail group and 3,000 from the letter group). We do not contact clients in the silent control group at this point. The decision to assign more clients from the mail group to the silent control group was taken due to financial constraints in contacting clients by letter. Thus, we will contact 13,500 clients by e-mail and 10,000 by letter, informing them of the planned interventions and asking them to express their interest and provide some organizational details through an online survey. (Update October 2024: 25,982 clients contacted; 12,482 by letter, 13,500 by email; silent control group: 1725 clients). Given an estimated response rate of 2%, we anticipate up to 500 responses. Third, of those 500 responding clients, we will randomize assignment to the three treatment conditions subject to a number of constraints. Most importantly, only those participants who indicated that they would be able to participate in an in-person or family-based treatment could be randomized into such a treatment. We use the following randomization procedure: Respondents who state that they are unable to participate in any non-technical treatment (i.e., are unable to name a relative who would support them and are unable to attend an in-person course), are assigned to the traditional (baseline) treatment. Since their allocation is non-random, we will – depending on sample size – carefully conduct balance checks (s. pre-analysis plan), control for non-random allocation status and / or exclude this group from the analysis. Respondents who are able to participate in both non-technical treatments are randomly assigned between the baseline and non-technical treatment groups, obeying the capacity constraints for the non-technical treatment groups. Participants who are only able to participate in one non-technical treatment are randomly assigned between this treatment and the baseline treatment.
In case of a higher response rate than expected, we will 1) increase sample size in the baseline treatment group, 2) create a waitlist control group for the non-technical treatments, 3) introduce a third non-technical treatment group (i.e., a highly scalable video-based treatment). In case of an even lower response rate than anticipated, we will contact further potential participants from the silent control group, reducing its size. We will prioritize the groups as following (subject to cooperation restrictions with our partner): 1) non-technical group II, 2) baseline treatment group, 3) non-technical group I.
The relative in non-technical treatment group I receives 100 Euros in the form of a highly versatile gift voucher to account for his/her opportunity costs if the training has been completed. We choose to pay out vouchers rather than cash to comply with the bank’s internal guidelines. Recipients of the voucher can choose from a wide variety of e-commerce platforms, which ensures that a) the value of the voucher is comparable across individuals and b) the value of the voucher to the recipient approximates its nominal value.
The design of the platform for potential participants allows us to identify contacted people who download training material but do not participate in the first survey (and consequently, the actual intervention). If sufficiently large, we will investigate characteristics of this group and their IB use as a passive treatment group.
Stratification: Availability for in-person course during working hours, availability of a relative.
Update October 2024 (before final intervention data is available): We received 551 initial responses that could be merged to bank records. 333 participants met all participation criteria (complete responses, available for at least one non-technical treatment, sufficient language skills to follow training, sufficient access to IB technology) and were randomized into treatment groups (stratification see above). They constitute our main sample, which we check for balance across treatment groups with respect to gender, age, and bank account inflows. The remaining initial respondents were also assigned to treatment groups and constitute an expanded sample used in additional analyses.
The anticipated timeline is as follows:
• June 14, 2024: Collection of login and transaction logs for all clients aged 40 and older by the bank for the month before, transmitted to authors in anonymized form (using project ID).
• June, 2024: Selection of sub-sample eligible for interventions as well as random allocation to silent control group by the authors, transmission of project IDs to be contacted by letter and e-mail to bank.
• July 12, 2024: Initial contact letters / e-mails delivered
• August 5, 2024: Deadline for completing registration survey
• August, 2024: Evaluation of responses, randomization into treatment groups (see above)
• Early October, 2024: Second contact (including pre-survey link and booking platform for non-technical treatment group II)
• October 21 – 30, 2024: On-site interventions (non-technical group II)
• November 04, 2024: Deadline for claiming a voucher after successful training completion (non-technical group I)
• Early December 2024 and January 2025 (expected?): Collection of login and transaction logs for all clients in sub-sample eligible for intervention by the bank for the respective month before (November and December), transmitted to authors in anonymized form
• March 2024 (expected): Third contact (post-survey); if possible: additional collection of login and transaction logs as above