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Field
Trial End Date
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Before
January 17, 2020
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After
March 14, 2020
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Field
Last Published
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Before
December 06, 2019 03:36 PM
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After
December 21, 2019 02:24 PM
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Field
Intervention (Public)
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Before
In this RCT we exploit the naturally occurring exogenous variation in air pollution as our treatment intervention. Pollution episodes generally occur over a series of days, followed by wind-driven clean-air episodes. By exploiting this natural discontinuity in air pollution exposure, we are able to survey both treatment and control groups within a timeframe of several days. Participants will be randomly assigned to one of four groups, a low pollution (control group) or one of three high pollution treatment groups. The three high pollution treatment groups differ with respect to the magnitude of air pollution and whether a pollution alert was issued by the research team prior to the survey distribution. All participants will be notified via direct messages about the upcoming survey, 24-hours prior to survey distribution. Pollution and weather forecasts will be used to determine the exact distribution date of the experimental survey. We utilise the official Air Quality Index (AQI) classifications as a broad guideline to define objective pollution levels for each treatment group:
1) Participants in the low pollution control group will be invited to complete a set of incentivised tasks when air pollution levels are objectively low, with AQI values in the ‘Good’ to ‘Unhealthy for Sensitive Groups’ range. They will be notified 24-hours in advance about the upcoming survey.
2) Participants in the high pollution treatment group will be invited to complete the same set of incentivised tasks when air pollution levels are objectively high, with AQI values exceeding ‘Very Unhealthy’ levels of pollution. They will be notified 24-hours in advance about the upcoming survey.
3) Participants in the high_alert pollution treatment group will be invited to complete the same set of incentivised tasks at the same time as group (2). They will be notified 24-hours in advance about the upcoming survey and receive an additional warning message about the expected unhealthy levels of air pollution.
4) Participants in the high_max pollution treatment groups will be incited complete the same set of incentivised tasks when air pollution levels are extremely high, with AQI values in the ‘Hazardous’ range.
Absolute levels of pollution exposure may vary and AQI classifications will serve as a guideline only. To verify that official pollution levels are precise, we will take additional air quality measurements using modern air pollution measuring equipment located on the Campus of Renmin University.
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After
In this RCT we exploit the naturally occurring exogenous variation in air pollution as our treatment intervention. Pollution episodes generally occur over a series of days, followed by wind-driven clean-air episodes. By exploiting this natural discontinuity in air pollution exposure, we are able to survey both treatment and control groups within a time frame of several days. Participants will be randomly assigned to one of five groups, a low pollution (control group) or one of four high pollution treatment groups. The four high pollution treatment groups differ with respect to whether a pollution alert was issued by the research team prior to the survey distribution. All participants will be notified via direct messages about the upcoming survey, 24-hours prior to survey distribution. Pollution and weather forecasts will be used to determine the exact distribution date of the experimental survey. We utilise the official Air Quality Index (AQI) classifications as a broad guideline to define objective pollution levels for each treatment group:
1) Participants in the low pollution control group will be invited to complete a set of incentivised tasks when air pollution levels are objectively low, with AQI values in the ‘Good’ to ‘Unhealthy for Sensitive Groups’ range. They will be notified 24-hours in advance about the upcoming survey.
2) Participants in the high pollution treatment group will be invited to complete the same set of incentivised tasks when air pollution levels are objectively high, with AQI values exceeding ‘Very Unhealthy’ levels of pollution. They will be notified 24-hours in advance about the upcoming survey.
3) Participants in the high_alert pollution treatment group will be invited to complete the same set of incentivised tasks at the same time as group (2). They will be notified 24-hours in advance about the upcoming survey and receive an additional warning message about the expected unhealthy levels of air pollution.
4) Participants in the high_2 and high_alert_2 pollution treatment groups follow the same procedure as (2) and (3).
Absolute levels of pollution exposure may vary and AQI classifications will serve as a guideline only. To verify that official pollution levels are precise, we will take additional air quality measurements using modern air pollution measuring equipment located on the Campus of Renmin University.
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Field
Intervention End Date
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Before
January 17, 2020
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After
March 14, 2020
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Field
Experimental Design (Public)
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Before
The proposed RCT involves approximately 700 student participants enrolled at universities in Beijing, China. Data will be collected via online survey experiments using the Chinese messenger app 'WeChat'. Students will be contacted via direct messages and invited to participate in the study by following a link to an external survey platform. Once participants have completed the online survey, they will be immediately compensated via direct payment to their 'WeChat Wallets'.
We will implement an online between-subject experimental design in which students will be randomly assigned to a low pollution control group or one of three high pollution treatment (high, high_alert, high_max), using a stratified randomisation procedure. All four groups will be sampled in December 2019. Participants will be notified 24-hours in advance about the upcoming survey via direct message. Participants in the high treatment condition will be sampled at the peak of a pollution episode. Participants in the high_alert treatment condition will be sampled at the same time but will have received an additional pollution alert with the survey notification (24-hours prior to the survey). Participants in the low pollution treatment conditions will be invited to complete the survey when air pollution levels are objectively low, immediately after the pollution episode. Participants in the high_max treatment condition will be sampled at the peak of a more extreme pollution episode. The exact sampling dates will be determined based on pollution and weather forecasts.
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After
The proposed RCT involves approximately 700 student participants enrolled at universities in Beijing, China. Data will be collected via online survey experiments using the Chinese messenger app 'WeChat'. Students will be contacted via direct messages and invited to participate in the study by following a link to an external survey platform. Once participants have completed the online survey, they will be immediately compensated via direct payment to their 'WeChat Wallets'.
We will implement an online between-subject experimental design in which students will be randomly assigned to a low pollution control group or one of four high pollution treatment (high, high_alert, high_2, high_alert_2), using a stratified randomisation procedure. All five groups will be sampled in December 2019. Participants will be notified 24-hours in advance about the upcoming survey via direct message. Participants in the high treatment condition will be sampled at the peak of a pollution episode. Participants in the high_alert treatment condition will be sampled at the same time but will have received an additional pollution alert with the survey notification (24-hours prior to the survey). Participants in the low pollution treatment conditions will be invited to complete the survey when air pollution levels are objectively low, immediately after the pollution episode. To collect additional data for our high-pollution treatment conditions, high_2 and high_alert_2 are sampled at the peak of a second pollution episode at the end of December 2019. The exact sampling dates will be determined based on pollution and weather forecasts.
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Field
Sample size (or number of clusters) by treatment arms
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Before
The sample will be equally split between all four groups.
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After
The expected sample size for each high-pollution treatment arm is approximately 250 participants per treatment (combined high and high_alert treatment groups). The sample size for the low-pollution control group is 169.
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