Messaging to Encourage Signup of Text Alerts for Air Quality

Last registered on February 28, 2025

View Trial History

Pre-Trial

Trial Information

General Information

Title

Messaging to Encourage Signup of Text Alerts for Air Quality

RCT ID

AEARCTR-0015447

Initial registration date

February 25, 2025

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published

February 28, 2025, 10:47 AM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Country

United States of America

Region

California

Primary Investigator

Name

Collin Weigel

Affiliation

California Air Resources Board

Contact Primary Investigator

Other Primary Investigator(s)

Additional Trial Information

Status

On going

Start date

2024-07-16

End date

2025-03-21

Keywords

Behavior, Environment & Energy, Health

Additional Keywords

Air Pollution, RCT, Messaging, Language

JEL code(s)

Q53; C93; Z13

Secondary IDs

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

In partnership with Santa Barbara County Air Pollution Control District (SBCAPCD), the California Air Resources Board (CARB) sent letters to residents encouraging them to sign up for air quality alerts via text message or email. The alerts are sent in both English and Spanish and notify residents of air quality issues and prescribed burns. In our analysis, we will compare sign-up rates across different messages to determine how differences affect take up in the mailing campaign. The empirical results can help agencies better engage constituents, particularly in Spanish-speaking communities.

External Link(s)

Registration Citation

Citation

Weigel, Collin. 2025. "Messaging to Encourage Signup of Text Alerts for Air Quality." AEA RCT Registry. February 28. https://doi.org/10.1257/rct.15447-1.0

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

We will send mailers to households encouraging them to sign up for a text and email alert system that notifies them about air quality events.

Intervention (Hidden)

Intervention Start Date

2024-07-16

Intervention End Date

2025-02-13

Primary Outcomes

Primary Outcomes (end points)

Signup for air quality alerts by text or email.

Primary Outcomes (explanation)

This is the goal of the campaign.

Secondary Outcomes

Secondary Outcomes (end points)

None

Secondary Outcomes (explanation)

Experimental Design

We employed a 2x2 factorial design in which we randomly varied (1) language and (2) framing in the letters based on the implementation partner’s interests. For language, we implemented two versions of the letter; both versions contained descriptions in both English and Spanish, but the two versions differed in which language was prominently featured. For framing, one version of the letters emphasized that it is “easy to sign up.” In the other version, the letters emphasized that signing up for the alert would help “protect your family.” We note, however, that we only focus on the language variation in our analysis given the set of research questions we pre-specify.

Experimental Design Details

Randomization Method

Randomization done in office by a computer.

Randomization Unit

Household

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

Sample size: planned number of observations

10,000

Sample size (or number of clusters) by treatment arms

2,500

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

We anticipate a 1.5% sign-up rate and explore power for 0.6 (0.05 SD) and 1.2 (0.1 SD) percentage-point effect sizes. We estimate that power for a sample size of 10,000 is 62% and 99%, respectively. Power for a given effect size in terms of percentage points increases as the baseline rate decreases. For example, for a 0.6% effect size and a baseline sign-up rate of 2.5% we estimate power to be 45%.

Supporting Documents and Materials

IRB