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Field
Trial Start Date
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Before
March 02, 2020
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After
July 03, 2020
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Field
Trial End Date
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Before
July 17, 2020
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After
July 31, 2020
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Field
Last Published
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Before
February 21, 2020 11:54 AM
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After
July 03, 2020 12:24 AM
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Field
Intervention Start Date
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Before
March 22, 2020
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After
July 03, 2020
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Field
Intervention End Date
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Before
May 29, 2020
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After
July 31, 2020
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Field
Primary Outcomes (End Points)
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Before
The amount gambled ($) over 84 gambles
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After
The amount gambled ($) over 56 gambles
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Field
Primary Outcomes (Explanation)
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Before
This is a continuous measure. It is the total amount bet (lab $) over 84 gambles (gamble 13 to gamble 96) by each individual, averaged within each experimental group. The largest amount that can be gambled for each gamble is 10 lab dollars so the range of this variable will be 0 to 840 lab dollars.
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After
This is a continuous measure. It is the total amount bet (lab $) over 56 gambles (gamble 9 to gamble 64) by each individual, averaged within each experimental group. The largest amount that can be gambled for each gamble is 15 lab dollars so the range of this variable will be 0 to 840 lab dollars.
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Field
Power calculation: Minimum Detectable Effect Size for Main Outcomes
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Before
Power calculations are for alpha of 0.05, power 80% and a one-sided test. We are calculating power for a one-sided test because we are only interested in seeing if the interventions lead to a reduction in mean amount gambled compared to the control group. We are aiming to recruit 1,500 participants for the trial. With 500 participants for each arm with three arms, we will be able to detect a small standardized effect size (Cohen’s d) of 0.25 – if it exists – for both the mean amount bet and the mean number of bets made.
If we are unable to recruit as many participants as hoped, we will only be able to detect larger effect sizes (e.g. Cohen’s d>0.25) if such an effect exists.
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After
Power calculations are for alpha of 0.05, power 80% and a two-sided test. We are aiming to recruit 1,500 participants for the trial. With 500 participants for each arm with three arms, we will be able to detect a small standardized effect size (Cohen’s d) of 0.25 – if it exists – for both the mean amount bet and the mean number of bets made.
If we are unable to recruit as many participants as hoped, we will only be able to detect larger effect sizes (e.g. Cohen’s d>0.25) if such an effect exists.
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