# Situation: A public health nurse at the Rural Health Unit (RHU) is preparing a study of handwashing and diarrhea among children under 5 years in a municipality of 18 barangays. She has a complete list of households in each barangay. She reads a report in which the provincial health office itself chose the 10 barangays with the most diarrhea cases to receive a new school handwashing program, while 10 other barangays continued their usual activities. Diarrhea incidence among children in the two groups of barangays was compared over the next year. How is this design classified?

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> subject: Nursing Practice I — Community Health Nursing

## 문제

Situation: A public health nurse at the Rural Health Unit (RHU) is preparing a study of handwashing and diarrhea among children under 5 years in a municipality of 18 barangays. She has a complete list of households in each barangay.

She reads a report in which the provincial health office itself chose the 10 barangays with the most diarrhea cases to receive a new school handwashing program, while 10 other barangays continued their usual activities. Diarrhea incidence among children in the two groups of barangays was compared over the next year. How is this design classified?

## 보기

1. Nonrandomized community trial **✔ 정답**
2. Ecological correlation study
3. Cluster randomized trial
4. Prospective cohort study

**정답: 1**

## 해설

The investigators decided which barangays received the program, so the study is experimental (an intervention study), not observational. Because whole communities were assigned but not by random allocation, it is a nonrandomized (quasi-experimental) community trial. Choosing the worst-affected barangays means the groups may differ at the start, so its evidence is weaker than that of a randomized trial.

## 심화 해설

Study design classification

The scenario describes an intervention study in which the provincial health office assigned whole barangays to receive a school handwashing program or to continue usual activities, and then compared diarrhea incidence between the two groups over the following year. The key feature is that the assignment was made by the investigators, not by chance, and the unit of assignment was the community rather than the individual child.

Because the investigators decided which barangays received the program, this is an experimental design, not an observational one. The term “experimental” in epidemiology means that the researcher controls the exposure. In contrast, a cohort study would simply observe handwashing practices that already exist without assigning them.

The correct classification is a nonrandomized community trial, also called a quasi-experimental community trial. The word “community” reflects that entire barangays were allocated as clusters, while “nonrandomized” reflects that the provincial health office selected the intervention barangays based on having the most diarrhea cases rather than using a random process.

Watch out! A cluster randomized trial would require random allocation of barangays to intervention or control. Here, the selection was deliberate and based on disease burden, so randomization is absent.

Key point! Selecting the 10 barangays with the most diarrhea cases introduces a major threat to validity. These barangays may differ from the comparison barangays in sanitation, water access, health-seeking behavior, or socioeconomic status at baseline. Because the groups may not be comparable at the start, the evidence from this design is weaker than that from a randomized trial.

| Design feature | Nonrandomized community trial | Cluster randomized trial | Prospective cohort study | Ecological correlation study |
| --- | --- | --- | --- | --- |
| Investigator assigns exposure | Yes | Yes | No | No |
| Unit of assignment | Community | Community | Individual | Group or population |
| Allocation method | Deliberate or convenience | Random | Not applicable | Not applicable |
| Main weakness | Baseline differences between groups | Fewer weaknesses; stronger evidence | Confounding by indication | Ecological fallacy |

The term quasi-experimental is used in the literature to describe exactly this kind of design. In a multi-country study of community-oriented handwashing interventions, the authors explicitly described their approach as a quasi-experimental multi-country study with matched comparisons, where intervention sites were selected and then compared with matched control sites [2]. Similarly, a sanitation and hygiene intervention in Ethiopia was conducted as a community-based quasi-experimental study among households, with intervention and comparison groups chosen by the research team rather than by random assignment [4]. A non-randomised cluster trial of a WaSH intervention in rural India also used the label quasi-experimental, non-randomised cluster study to signal that clusters were assigned without randomization [3].

These examples reinforce the classification logic for the licensure exam. When the question states that the health office chose the barangays and the outcome is compared over time, the design is experimental because an intervention was delivered, but the absence of random allocation makes it nonrandomized. The fact that the intervention was delivered at the school or barangay level, with outcomes measured in children, confirms that the community is the unit of assignment.

The reason this design produces weaker evidence than a randomized trial is that the selection of high-burden barangays may create systematic differences between groups at baseline. Any observed reduction in diarrhea could be due to the intervention, but it could also be due to regression to the mean, secular trends, or pre-existing differences in risk factors. A randomized design would balance both measured and unmeasured confounders across the two groups, which is why randomization is preferred when feasible [1].References (research sources)

- [1]An Overview of Research and Evaluation Designs for Dissemination and Implementation.Research articleBrown CH, Curran G, Palinkas LA, Aarons GA, Wells KB, Jones L (2017) · DOI: 10.1146/annurev-publhealth-031816-044215

- [2]Association of mother's handwashing practices and pediatric diarrhea: evidence from a multi-country study on community oriented interventions.Research articleEdward A, Jung Y, Chhorvann C, Ghee AE, Chege J (2019) · DOI: 10.15167/2421-4248/jpmh2019.60.2.1088

- [3]Effect of the sanitation, hygiene, information, and education intervention on WaSH practices and related health outcomes among children in rural Anganwadi centres: a non-randomised cluster trial pilot tested in Odisha, India.RCT/clinical trialKar S, Singh S, Ray A, Pattnaik B, Das S, Das A (2025) · DOI: 10.3389/fpubh.2025.1676981

- [4]Effects of community-led total sanitation and hygiene implementation on diarrheal diseases prevention in children less than five years of age in South Western Ethiopia: A quasi- experimental study.Research articleBushen G, Merga H, Tessema F (2022) · DOI: 10.1371/journal.pone.0265804

## 임상 시나리오

Nonrandomized Community Trial DesignRecognizing quasi-experimental allocation of barangays
When investigators assign whole communities to intervention or control without random allocation, the design is a nonrandomized community trial. The unit of assignment is the barangay, not the individual child.

The key distinction from a cluster randomized trial is the absence of chance-based allocation. Deliberate selection of the 10 barangays with the most diarrhea cases makes this quasi-experimental, not truly randomized.

CautionSelecting the worst-affected barangays introduces selection bias and threatens internal validity. Groups may differ at baseline in ways that affect diarrhea incidence, so evidence is weaker than from a randomized trial.

## 핵심 개념

- **Nonrandomized community trial** — An experimental study where whole communities are assigned to intervention or control by investigator choice, not by chance.
- **Cluster randomized trial** — A trial where groups (clusters) such as barangays are randomly allocated to intervention or control.
- **Quasi-experimental design** — A study design that tests an intervention without random assignment of participants or groups.
- **Ecological study** — An observational study that analyzes data at the group or population level rather than individual level.
- **Selection bias** — Systematic difference between groups being compared due to how participants or clusters were chosen.

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