Experimental Design Details
This is a survey experiment. Participants are recruited online and provide us with demographic information. We then inform them about carbon offsets, in case they are unfamiliar.
From here, first- and second-order beliefs on market share of carbon offsets are elicited in an incentivized manner. To elicit beliefs, we first ask participants to guess how many people taking the survey self-reported having purchased a carbon offset before. This is incentivized for correctness. Since this measures how common each person thinks carbon offsets are, we refer to them henceforth as "first order beliefs." After this, we then ask people to guess what the average first order belief was, again incentivized for correctness. As these measure beliefs about beliefs, we refer to them as "second order beliefs." Second order beliefs are the beliefs which may impact social rewards, and are thus the beliefs which are of most pertinence to our study. We experimentally manipulate these beliefs by sending random signals to consumers and asking them what their posterior second order belief is after seeing the signal. These signals read "We previously surveyed 1,000 United States adults. In this previous survey, we found an average guess of [PROP] out of 1,000 people buying a carbon offset." Here, "[PROP]" randomly varies to be 14, 56, 128, 217, 315, or 438. These values come from averaging guesses in previous pilot studies we ran.
Finally, we give participants the choice between receiving a bonus payment or buying an offset, where some participants are told their action will yield their name being posted online while others are not. Each participant is given $1.50 for participation in the survey but told that they can offset about 145lbs. of carbon using Climate Vault's offsets (market price = $1.50) if they choose to do so. In order to do so, they must agree to forgo a randomly varying amount of their bonus payment. This amount varies to be $0.10, $0.70, or $1.40, allowing us variation in price to estimate demand. The participants are additionally randomized to be in a public group or private group. In the public group, those who buy carbon offsets will be allowed to provide their name to be posted online on a website of our design. The website is available at https://www.onset-of-offsets.com/. This website is promoted on an Instagram page with thousands of followers, as participants are informed. The Instagram page is available at https://www.instagram.com/onsetofoffsets/. The group who is not public will not have any of these options, they will just decide whether to purchase or not under status quo conditions.
From here, we ask several questions to determine which mechanisms drive the impact of name-posting as well as to determine endline beliefs about carbon offsets and the survey more specifically. We ask participants whether public name-posting is influenced by virtue signaling, privacy concerns, being seen as eco-friendly, or potentially promoting offset purchasing to others. The order of these four questions is randomized to ensure that no biases come that favor those questions which are presented first. After this, we ask participants whether they think their name will actually be seen by people. Finally, we conclude by asking participants whether they believe carbon offsets are effective and whether our survey was biased in any way.