Individual determinants of self protection among homeowners with(out) disaster risk insurance
Last registered on May 15, 2018


Trial Information
General Information
Individual determinants of self protection among homeowners with(out) disaster risk insurance
Initial registration date
May 07, 2018
Last updated
May 15, 2018 11:19 AM EDT

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Primary Investigator
Vrije Universiteit Amsterdam
Other Primary Investigator(s)
PI Affiliation
Vrije Universiteit Amsterdam
PI Affiliation
Vrije Universiteit Amsterdam
Additional Trial Information
In development
Start date
End date
Secondary IDs
The focus of this paper is to examine how the financial incentives emanating from insurance compare with the influence of other behavioral motivations for investing in flood risk reduction. The online lab-in-the-field experiment among homeowners in floodplains (N=2000) will demonstrate the effects of individual characteristics on risk mitigation decisions of relevant decision-makers. The expected results can be used to inform policy makers and insurance companies about how to stimulate people who voluntarily have flood insurance coverage to better prepare for flood disasters.
External Link(s)
Registration Citation
Blasch, Julia, Wouter Botzen and Jantsje Mol. 2018. "Individual determinants of self protection among homeowners with(out) disaster risk insurance." AEA RCT Registry. May 15.
Experimental Details
We will examine the effects of a premium discount and different types of insurance (mandatory, voluntary, no insurance) on damage reducing investments in an online experiment.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
damage reducing investments
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
willingness to pay for flood insurance
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
We use a short version of the investment game which was programmed for an earlier experiment. This investment game is followed by a final survey to gather data on risk preferences, time preferences and other behavioral factors that could be important characteristics related to flood risk.
Experimental Design Details
Not available
Randomization Method
randomization done by oTree software
Randomization Unit
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
5 treatments
Sample size: planned number of observations
The sample targets 2000 homeowners who are located in the river delta areas of the Netherlands with flood probability standard of 1 in 1250.
Sample size (or number of clusters) by treatment arms
At least 300 homeowners per treatment. Exact sample size per treatment will be determined after a pilot with 100 observations in the Voluntary treatment.
The pilot results showed that about 25% of homeowners in the Voluntary treatments self selects into Insurance. No major changes were made in the design after the pilot results. We aim for at least 150 homeowners self selected into Voluntary Insurance and Voluntary Insurance Discount. For the premium discount versus Mandatory Insurance we expect a larger effect size. Therefore we will sample:

300 No Insurance
300 Baseline
200 Premium Discount
600 Voluntary
600 Voluntary Discount
2000 in total (or more if budget allows)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
A sample size analysis assuming an alpha of 0.05 and a power of 80% indicated that we need a sample size of at least 252 participants per treatment in order to detect the smallest effect size* found in the scenario of a previous lab experiment, closest to our current parameters, with a Wilcoxon Mann Whitney test. * Mean investments in ECU in previous experiment No Insurance versus Mandatory Insurance: 2711.9 (sd 4102.4) versus 1793.4 (sd 3976.8): effect size 27% -> sample size needed 252 * Mean investments in ECU in previous experiment Mandatory Insurance versus Premium Discount: 1793.4 (sd 3976.8) versus 3550 (sd4560.1): effect size 41% -> sample size needed 78
IRB Name
IRB Approval Date
IRB Approval Number