The effect of peer earnings information on wage expectations
Last registered on November 13, 2020

Pre-Trial

Trial Information
General Information
Title
The effect of peer earnings information on wage expectations
RCT ID
AEARCTR-0006732
Initial registration date
November 13, 2020
Last updated
November 13, 2020 8:33 AM EST
Location(s)
Primary Investigator
Affiliation
Development Economics Research Group, Copenhagen University
Other Primary Investigator(s)
PI Affiliation
UNU-WIDER
Additional Trial Information
Status
On going
Start date
2019-10-02
End date
2020-12-01
Secondary IDs
Abstract
How do secondary school graduates’ wage expectations react to different types of new information? In this study, we review the effect of information on the evolution of future earnings expectations. We use a randomised control trial which exposes individuals to different information treatments over the period, based on data collected from prior survey rounds. The RCT is conducted with a large sample of Mozambican secondary school leavers from technical and vocational education institutes who are part of an on-going tracer study as they transition from school to the labour market.
External Link(s)
Registration Citation
Citation
Jones, Sam and Ricardo Santos. 2020. "The effect of peer earnings information on wage expectations." AEA RCT Registry. November 13. https://doi.org/10.1257/rct.6732-1.0.
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Experimental Details
Interventions
Intervention(s)
The experiment will focus on how individuals update their wage expectations in response to different types of information about the actual income distribution. Groups of students, who are part of an on-going phone survey which is tracking their progression from school to work, will be sent information on average earnings by SMS. There will be three different messages which are sent out:
1) A general message: summarises wage information from the entire sample of students
2) A school type specific message: summarises wage information from the sub-sample of participants that attended the same school type as the recipient (public/private)
3) A field-specific message: summarises wage information from the sub-sample of participants in the same study field as the participant.

The wage information shared will be the most recent results from the on-going tracer study of technical and vocational students across Mozambique. Note, the specific information contained in each SMS varied by survey round; and, in the second and third types of message, the information varied by individual according to the school type they had attended or their field of training. Mirroring variation in actual wages, this design provides for substantial variation in the underlying wage information received.
Intervention Start Date
2020-04-06
Intervention End Date
2020-09-22
Primary Outcomes
Primary Outcomes (end points)
We have three primary outcome variables: beliefs about current peers' earnings, current reservation wage, and future own-earning beliefs (expected wage at the end of 2020).
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Directly after the baseline survey, which was conducted in October 2019, individuals were randomly-allocated to one of five experimental arms (including the control). The four treatment arms are distinguished by the type of messages they would receive. Specifically:
• Group one (general): received the general (all-student) message in all relevant rounds;
• Group two (school-type): received the school-type-specific message in all relevant rounds;
• Group three (field): received the field-specific message in all relevant rounds; and
• Group four (mixed): received the general message in round two, the school-type specific message in rounds three and four, and the field-specific message in rounds five and six.

The full sample is being tracked as part of a broader tracer study, where, on a quarterly basis, the participants respond to a phone survey on their current employment situation. Through these phone surveys the outcome variables, as well as other valuable employment information, is tracked over time.
Experimental Design Details
Randomization Method
Randomisation conducted in STATA. Randomisation across the five experimental arms was stratified by study field and gender, with a
target of around 260 participants in the control group and 340 in each treatment arm.
Randomization Unit
Individual
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
1 control group (259 individuals), 4 treatment arms (each of approximately 340 individuals)
Sample size: planned number of observations
1,622 individuals
Sample size (or number of clusters) by treatment arms
Control group: 259 individuals
Treatment group 1: 337
Treatment group 2: 343
Treatment group 3: 342
Treatment group 4: 341
Total: 1,622
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Given the size of the experimental sample and the allocation into treatment arms, using an assumption that natural log of the expected wage in the control group equals 9.4 with a standard deviation of 0.7 (calculated from the baseline survey), the minimum detectable effect (at the 10% significance level) is 0.12 considering all treatment groups (combined). Or, for the smallest treatment group alone, the minimum detectable effect is a 0.14 log points. The former is about a three quarters the effect size found in Jones and Santos (2020).
Supporting Documents and Materials
Documents
Document Name
Design and pre-analysis plan
Document Type
other
Document Description
The effect of peer earnings information on wage expectations: Design and pre-analysis plan
Sam Jones and Ricardo Santos; UNU-WIDER; November 2020
File
Design and pre-analysis plan

MD5: cc87eedac9ab8221d8c2d158e487feca

SHA1: abd6bf03aa56ad8e0f5826bd66b2ad41b2cea5b8

Uploaded At: November 11, 2020

IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
IRB Approval Date
IRB Approval Number
Analysis Plan
Analysis Plan Documents
The effect of peer earnings information on wage expectations: Design and pre-analysis plan

MD5: cc87eedac9ab8221d8c2d158e487feca

SHA1: abd6bf03aa56ad8e0f5826bd66b2ad41b2cea5b8

Uploaded At: November 11, 2020

Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
No
Is data collection complete?
Data Publication
Data Publication
Is public data available?
No
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)
REPORTS & OTHER MATERIALS