|
Field
Abstract
|
Before
This study uses a cluster-randomized design to evaluate the effect of pretesting on learning and retention outcomes in a series of workshops conducted across seven sites. Workshops are randomized into two groups: one receiving a pretest, intervention, and posttest; the other receiving the intervention and posttest only. A follow-up assessment is administered to all participants one month later to measure knowledge retention. The primary outcomes are immediate post-intervention performance and one-month follow-up performance. Randomization was conducted using covariate-constrained allocation to achieve balance in expected attendance and regional representation.
|
After
This study uses a cluster-randomized design to evaluate the impact of an educational workshop on attitudes toward pollution taxation among university students. Seven workshop sites were randomized into two conditions: (i) a Test-Before-Workshop group, in which participants completed the survey instrument before attending the workshop; and (ii) a Test-After-Workshop group, in which participants completed the same survey instrument immediately after the workshop. To provide a true untreated comparison, a third group of students from similar campuses who did not attend any workshop completed the same survey during the same period. The primary outcome is variation in attitudes toward pollution taxation across these three groups, enabling estimation of both workshop effects and baseline differences. Cluster randomization used stratification by region and balancing on expected attendance to ensure comparability across conditions.
|
|
Field
Last Published
|
Before
July 17, 2025 08:00 AM
|
After
November 21, 2025 11:35 AM
|
|
Field
Intervention (Public)
|
Before
Intervention (Public)
The intervention is a structured educational workshop focused on the principles, design, and economic rationale of pollution taxes. The workshop is designed to improve participants’ understanding of environmental taxation, including its effectiveness, implementation challenges, and impact on behavior and market outcomes.
Workshops are delivered across seven clusters (locations), and each site receives the same curriculum, materials, and facilitator training to ensure consistency.
Clusters are randomly assigned to one of two groups:
Group A receives:
A pretest to assess baseline knowledge of pollution taxes.
The pollution tax workshop intervention.
An immediate posttest after the workshop.
A follow-up test one month later to assess retention.
Group B receives:
The pollution tax workshop intervention.
An immediate posttest after the workshop.
A follow-up test one month later.
The intervention aims to measure not only learning outcomes but also potential testing effects — i.e., whether taking a pretest improves posttest performance or knowledge retention.
|
After
The intervention consists of a structured educational workshop on the principles, design, and economic rationale of pollution taxes. The workshop is intended to improve participants’ understanding of environmental taxation, including its objectives, behavioral impacts, and implementation challenges. Workshops were delivered across seven university sites, each using the same curriculum, instructional materials, and facilitator training to ensure consistency in delivery.
Under the cluster-randomized design, the seven workshop sites were assigned to one of two conditions:
Group A – Test Before Workshop:
Participants completed the survey instrument once, immediately before participating in the workshop. The same instrument was not administered again afterward.
Group B – Test After Workshop:
Participants attended the same workshop and completed the same survey instrument once, immediately after the session.
In addition, a third comparison group was recruited at similar campuses where no workshop was delivered:
Group C – No Workshop + Test:
Participants did not attend the workshop but completed the same survey instrument during the same time period as Group B. This group serves as an untreated control for estimating workshop effects.
The intervention allows for estimation of differences in attitudes toward pollution taxation across groups that completed the same test under three conditions: before exposure, after exposure, and with no exposure at all.
|
|
Field
Primary Outcomes (End Points)
|
Before
Willingness to Pay (WTP) for Pollution Taxes (Immediate Posttest)
Measured via a 4-item behavioural intention scale based on TPB constructs. Score is computed as the average across items.
Change in WTP (Pre–Post, Group A only)
For Group A, willingness to pay is measured both before and immediately after the intervention. Change is calculated as the difference in composite scores.
Posttest WTP Comparison (Group A vs. B)
Between-group comparison of posttest WTP to assess the effect of pretesting on outcome levels.
WTP at 1-Month Follow-Up (All Participants)
Willingness to pay will be reassessed for both groups one month after the workshop. This allows evaluation of retention of intention and delayed effects of pretesting. Group-level comparisons and within-person (for Group A) change from posttest to follow-up will be analyzed.
Moderation by Pro-Environmental Behavior
A 12-item index capturing baseline environmental behavior will be tested as a moderator of both immediate and follow-up WTP outcomes.
Heterogeneous Effects by Demographics
Gender, religion, income, and other background variables will be explored as moderators of WTP outcomes.
|
After
Primary Outcome: Willingness to Pay (WTP) for Pollution Taxes
The primary outcome is Willingness to Pay (WTP) for pollution taxes, measured using a 4-item behavioral intention scale based on Theory of Planned Behavior constructs. Each item is rated on a 7-point Likert scale, and a composite WTP score is computed as the mean of all items (after reverse-coding where applicable).
Because each participant completes the survey once, WTP is observed under three conditions:
Before the workshop (Group A)
After the workshop (Group B)
Without any workshop exposure (Group C)
These comparisons allow estimation of:
Workshop Effect:
Difference in WTP between Group B (workshop + test after) and Group C (no workshop + test).
Baseline vs. Post-Workshop Differences (Descriptive):
Comparison of Group A (test before) and Group B (test after).
Baseline vs. Non-Workshop Posttest Differences:
Comparison of Group A and Group C to assess whether untreated posttest attitudes differ from baseline levels.
Moderation Analyses
Two classes of moderators will be explored:
Pro-Environmental Behavior Index
A 12-item baseline measure capturing prior environmental behavior will be tested as a moderator of WTP differences across groups.
Demographic Moderators
Gender, religion, income, academic discipline, and other background variables will be examined for heterogeneous effects on WTP across conditions.
|
|
Field
Primary Outcomes (Explanation)
|
Before
Willingness to Pay (WTP) for Pollution Taxes
WTP is measured using a 4-item behavioral intention subscale, consistent with the Theory of Planned Behavior. Items include statements like:
“I intend to pay a pollution tax if it is introduced.”
“I plan to comply fully with a pollution tax policy.”
“I will likely avoid paying a pollution tax when required.” (reverse-coded)
Each item is rated on a 7-point Likert scale, and the composite WTP score is calculated as the mean of the items (after reverse-coding where applicable). This is measured:
Immediately after the workshop (posttest) for all participants, and
One month later to assess retention of willingness to pay.
Change in WTP (Pre-Post, Group A only)
For participants in Group A (who receive a pretest), change in WTP is calculated as the difference between posttest and pretest composite WTP scores.
Long-Term Retention (Follow-Up WTP)
The WTP measure is repeated at a 1-month follow-up for both groups. For Group A, change scores (pre vs. follow-up, and post vs. follow-up) can be calculated. For Group B, follow-up WTP offers a delayed outcome measure not influenced by pretesting. This allows exploration of whether the initial test exposure affects retention.
Moderation and Heterogeneity
Pre-intervention pro-environmental behavior (12-item index) will be used as a moderator of WTP outcomes. Demographics (e.g., gender, income, religion) will also be used in subgroup analyses.
TPB Constructs as Exploratory Mechanisms
Attitudes, subjective norms, perceived behavioral control, and moral norm (each measured by 4 items) will be examined as potential mediators or moderators of WTP outcomes but are not primary endpoints themselves.
|
After
Willingness to Pay (WTP) for pollution taxes is measured using a 4-item behavioral intention scale adapted from the Theory of Planned Behavior. Items include intention to comply with pollution taxes, likelihood of paying required charges, and related behavioral commitments. Each item is scored on a 7-point Likert scale; the composite score is the mean of all items (reverse-coding when necessary).
Because each participant completes the survey once, the WTP measure is observed under three conditions:
Before workshop exposure (Group A)
After workshop exposure (Group B)
Without workshop exposure (Group C)
This structure allows for:
Causal estimation of the workshop effect through comparison of Group B vs. Group C
Descriptive baseline vs. post-workshop differences by comparing Group A vs. Group B
Baseline vs. untreated posttest differences by comparing Group A vs. Group C
Moderation analyses using demographic variables and a pro-environmental behavior index will examine heterogeneity in WTP across groups
|
|
Field
Experimental Design (Public)
|
Before
This is a cluster-randomized field experiment conducted across seven university workshops. Clusters (workshops) are randomly assigned to one of two groups:
Group A: receives a pretest, the pollution tax workshop, a posttest, and a 1-month follow-up.
Group B: receives the same workshop, a posttest, and a 1-month follow-up, but no pretest.
The design allows for comparison of outcomes across and within groups, including follow-up measurement of retention
|
After
This study adopts a three-arm between-subjects experimental design, implemented across seven university workshop sites and an additional non-workshop comparison group. Participants complete the same survey instrument once, but at different points relative to the workshop intervention.
The three groups are:
Group A – Test Before Workshop
Participants completed the survey immediately before the workshop session.
Group B – Test After Workshop
Participants attended the same workshop and completed the survey immediately after the session.
Group C – No Workshop + Test
Participants did not attend any workshop but completed the same survey during the same time window.
This structure enables estimation of workshop effects and comparisons of baseline, post-treatment, and untreated attitudes toward pollution taxation.
|
|
Field
Randomization Method
|
Before
Randomization was done in office by computer using a covariate-constrained algorithm written in Python. All possible 3:4 allocations of clusters were evaluated, and the assignment that minimized imbalance on expected attendance and regional representation was selected
|
After
Randomization was implemented at the workshop (cluster) level using a stratified and attendance-balanced allocation procedure:
Workshops were stratified into North (3) and South (4) regions.
Within each stratum, workshops were randomly assigned to either:
Test-Before Workshop (Group A) or
Test-After Workshop (Group B)
To prevent imbalance in sample sizes, a greedy balancing algorithm was applied using expected attendance. Workshops were sorted by anticipated size and iteratively assigned to the condition with the lower cumulative attendance within each region.
Group C was not randomized; it serves as an external untreated comparison sample recruited to establish a counterfactual.
|
|
Field
Randomization Unit
|
Before
Randomization was conducted at the cluster level, where each cluster corresponds to a university workshop session. All participants within a given workshop were assigned to the same experimental condition. No individual-level randomization was used.
|
After
The randomization unit is the workshop site (cluster).
All participants at a given workshop location were assigned to the same condition (A or B). Group C participants were surveyed outside the workshop setting.
|
|
Field
Planned Number of Clusters
|
Before
7 clusters (workshops), with approximately 3 assigned to the pretest group (Group A) and 4 to the posttest-only group (Group B).
|
After
Randomized clusters: 7 workshop sites
Group A: 3 clusters
Group B: 4 clusters
Non-randomized comparison sites: Group C (independent sample)
Planned total sample: ~1,200 students (≈500 for group A & B, 200 for group C)
Exact totals may vary depending on final attendance and recruitment.
|
|
Field
Planned Number of Observations
|
Before
Approximately 1,200 university students, based on expected attendance figures across the 7 workshop clusters.
|
After
Approximately 1,000 university students, based on expected attendance figures across the 7 workshop clusters.
|
|
Field
Sample size (or number of clusters) by treatment arms
|
Before
Group A (Pretest + Posttest + Follow-Up): 3 clusters, approximately 600 students
Group B (Posttest + Follow-Up only): 4 clusters, approximately 600 students
|
After
Group A (Before the Workshop): 3 clusters, approximately 500 students
Group B (After the Workshop): 4 clusters, approximately 500 students
|
|
Field
Power calculation: Minimum Detectable Effect Size for Main Outcomes
|
Before
Power Calculation: Minimum Detectable Effect Size for Main Outcomes
Assuming:
7 clusters (3 in Group A, 4 in Group B)
600 students per group (≈85–215 per cluster)
Intra-cluster correlation (ICC): 0.01–0.05 (typical for attitudinal survey outcomes)
Two-sided α = 0.05, power = 0.80
Standard deviation (SD) of WTP scale: assumed to be 1.0 (standardized Likert-based composite)
The minimum detectable effect size (MDES) is approximately:
Standardized effect size (Cohen’s d): 0.30–0.35, depending on ICC
This translates to about 30–35% of one standard deviation in WTP or TPB-based scale scores.
Power was calculated using formulas for two-group comparisons in clustered designs, accounting for unequal cluster sizes and between-group allocation (3 vs. 4 clusters).
|
After
Assumptions:
7 clusters randomized to Groups A and B
Group C treated as an independently sampled comparison group
Intra-cluster correlation (ICC) for attitudinal outcomes: 0.01–0.05
α = 0.05, power = 0.80
Standard deviation of WTP ≈ 1.0 (standardized Likert composite)
Under these assumptions, the design can detect a standardized mean difference (Cohen’s d) of:
d ≈ 0.30–0.35 for comparisons between Groups A and B
d ≈ 0.20–0.30 for comparisons involving Group C (due to larger effective sample)
|
|
Field
Intervention (Hidden)
|
Before
Intervention (Hidden)
Participants are not informed of their assignment to different study groups or of the existence of a pretest-only group. The study is presented uniformly as a workshop on pollution taxes followed by a knowledge assessment. This design is intended to minimize expectancy effects and differential engagement.
In Group A, the pretest is administered as a standard entry activity. In Group B, no mention is made of the pretest, and participants only encounter the assessment at the end. The one-month follow-up is framed as a general feedback and learning review to reduce test-related bias.
The covariate-constrained randomization approach was conducted before the workshops using a pre-specified script that minimized imbalance in expected attendance and regional representation. Workshop facilitators are blind to the allocation strategy.
|
After
Participants were not informed of the existence of different survey-timing conditions or of the inclusion of a separate non-workshop comparison group (Group C). The study was presented uniformly as an educational project on pollution taxes with an accompanying survey measuring student attitudes.
In Group A, the survey instrument was administered as a standard pre-session activity before the workshop began. No indication was given that other participants might complete the survey at a different time.
In Group B, the same survey instrument was administered only after the workshop. Participants in this group were not informed that some workshops had completed the survey beforehand.
In Group C, students were surveyed in comparable campus settings without being informed that they constituted a non-workshop comparison group. The survey was presented simply as part of a study on environmental taxation attitudes.
Randomization of workshop sites into Groups A and B was conducted in advance using a stratified and attendance-balanced allocation procedure. Facilitators were blind to the randomization process and to the purpose of differing survey timings.
|
|
Field
Secondary Outcomes (End Points)
|
Before
Theory of Planned Behavior Constructs (Posttest and Follow-Up)
These include:
Attitudes toward pollution taxes
Subjective norms
Perceived behavioral control
Moral norm
Each construct is measured with 4 Likert-scale items (1–7 scale) and scored as the mean of the relevant items (after reverse-coding where needed).
They will be analyzed as:
Exploratory secondary outcomes (changes from pretest to posttest and follow-up)
Potential mediators of the effect of the intervention on WTP;
Workshop Evaluation (Posttest Only)
At the end of the workshop, participants rate:
Clarity of the workshop content
Perceived usefulness for understanding pollution taxes
Likelihood of recommending the workshop to others
These are measured on Likert scales and will be used for descriptive and internal evaluation purposes only.
Changes in TPB Constructs Over Time
For participants with pretest and follow-up data (Group A), changes in attitudes, norms, control, and moral obligation will be tracked to explore how stable these constructs are post-intervention and how they relate to sustained WTP.
|
After
Secondary outcomes include:
Theory of Planned Behavior (TPB) Constructs
Attitudes toward pollution taxes
Subjective norms
Perceived behavioral control
Moral norms
Each construct is measured using four Likert-scale items (1–7), averaged into composite scores.
Workshop Evaluation (Groups A and B only)
Items measuring perceived clarity, usefulness, interest, and likelihood of recommending the workshop. These are descriptive outcomes.
Heterogeneous Effects
The effect of the workshop across demographic characteristics (gender, income, religion, year of study, academic discipline).
Moderation by Pro-Environmental Behavior
A 12-item scale capturing prior environmentally friendly behaviors.
|
|
Field
Secondary Outcomes (Explanation)
|
Before
TPB Construct Scores
Each Theory of Planned Behavior construct (attitudes, subjective norms, perceived behavioral control, moral norm) is measured using 4 Likert-scale items (7-point scale). Scores are computed as the mean of the items within each construct, after reverse-coding negatively worded items. These scores will be analyzed:
As outcomes in their own right (pre-post and post-follow-up)
As potential mediators in models predicting willingness to pay (WTP)
Workshop Evaluation Metrics
Three post-intervention Likert items assess perceived clarity, usefulness, and likelihood of recommendation. Each item is treated as an individual ordinal outcome. These will be used descriptively to inform future improvements to workshop delivery but are not inferential endpoints.
Longitudinal Change in TPB Constructs
For participants with complete pretest, posttest, and follow-up data (Group A), within-subject change scores will be calculated for each TPB construct. These will be used to assess persistence or decay of psychological constructs over time.
Let me know when you’re ready to move on to the Analysis Plan or revisit any earlier registry section!
|
After
TPB constructs provide insight into psychological mechanisms underlying willingness to pay. Each construct is measured with four Likert-scale items, reverse-coded when appropriate. These constructs will be analyzed as:
Additional outcomes of interest
Moderators of the workshop effect
Potential explanatory variables in multivariate models
Workshop evaluation items provide feedback on the clarity and perceived usefulness of the session but are not used for formal hypothesis testing.
Demographic and behavioral moderators (e.g., prior environmental behavior) allow exploration of how workshop effects vary across subpopulations.
|
|
Field
Pi as first author
|
Before
No
|
After
Yes
|