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Left-digit Bias in Wage Perceptions and Labor Supply in an Online Labor Market

Last registered on March 01, 2017

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Pre-Trial

Trial Information

General Information

Title

Left-digit Bias in Wage Perceptions and Labor Supply in an Online Labor Market

RCT ID

AEARCTR-0001349

Initial registration date

July 06, 2016

Last updated

March 01, 2017 1:32 PM EST

Location(s)

Country

United States of America

Region

Primary Investigator

Name

Suresh Naidu

Affiliation

Columbia University

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Other Primary Investigator(s)

PI Name

Alan Manning

PI Affiliation

LSE

Contact Investigator

PI Name

Arindrajit Dube

PI Affiliation

UMass Amherst

Contact Investigator

Additional Trial Information

Status

In development

Start date

2016-07-06

End date

2017-04-07

Keywords

Electoral, Labor

Additional Keywords

JEL code(s)

Secondary IDs

Abstract

We randomize wages for census image classification task to estimate discontinuous labor supply elasticities at round numbers---in particular at 10 cents, to test for left-digit bias. We also aim to replicate the upward sloping labor supply functions to a given task estimated in Horton et al (2011).

External Link(s)

Registration Citation

Citation

Dube, Arindrajit, Alan Manning and Suresh Naidu. 2017. "Left-digit Bias in Wage Perceptions and Labor Supply in an Online Labor Market." AEA RCT Registry. March 01. https://doi.org/10.1257/rct.1349-2.0.

Former Citation

Dube, Arindrajit, Alan Manning and Suresh Naidu. 2017. "Left-digit Bias in Wage Perceptions and Labor Supply in an Online Labor Market." AEA RCT Registry. March 01. https://www.socialscienceregistry.org/trials/1349/history/14601.

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

Intervention Start Date

2016-07-06

Intervention End Date

2016-10-07

Primary Outcomes

Primary Outcomes (end points)

Indicator for accepting MTurk task. Time to complete task. Error rate in tagging.

Primary Outcomes (explanation)

Error rate will be calculated using 2 "known positives" that will be randomly assigned to workers.

Secondary Outcomes

Secondary Outcomes (end points)

Secondary Outcomes (explanation)

Experimental Design

We will post a total of 5,500 unique HITS on MTurk tasks for $0.10 that includes a brief survey and a screening task, where respondents view a digital image of a historical slave census schedule from 1850 or 1860, and answer whether they see markings in the “fugitives” column. Some respondents are offered a choice of completing an additional set of classification tasks for a specific wage.

Extension: we have also run a version of this experiment with a recipe tagging task, at 90, 99, 100, 101, and 110 cents.

Experimental Design Details

We refer to the initial screening part as “stage-1.” Those who complete stage-1 and indicate that the primary reason for participation is "money" or "skills" (as opposed to "fun") are then offered an additional task of completing either 6 or 12 such image classifications (chosen randomly) for a specific (randomized) wage, w, which we refer to as "stage-2." If they accept the stage-2 offer, they are provided either 6 images (task type A) or 12 images (task type B) to classify, and are paid the wage w. These 5,500 HITs will remain posted until completed, or for 3 months, which ever is shorter. Any single individual on mTurk (identified by their MTurk ID) will be allowed to only do one of the HITs. We aim to assess the left-digit bias in wage perceptions experimentally by randomizing the offered wages for HITs on MTurk by randomizing a wage offer for a HIT to vary between $0.05 and $0.15, and assessing whether there is a jump in the acceptance probability between $0.09 and $0.10 as would be predicted by a left-digit bias.

Randomization Method

Randomization done by computer that automatically posts task on Amazon turk.

Randomization Unit

individual MTurk worker.

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

5500

400 for extension

Sample size: planned number of observations

5500 400 for extension

Sample size (or number of clusters) by treatment arms

5500

400 for extension