AmeriCorps Research 

Guidance 

May 2019

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How to Fully Describe an 

Intervention

Nan Maxwell

Learn how to thoroughly describe your intervention to funders and 

stakeholders. 

Developers design an intervention to be implemented in a standardized way (the 

intervention model) and for specific individuals or groups (the target population). 

They develop it to produce specific knowledge, attitudes, or behaviors or improve 

specific outcomes. For an organization to implement an intervention consistently, it is 

critical that developers clearly articulate its model. Indeed, a well-defined intervention 

helps an organization produce a consistent set of outcomes for participants and 

successfully expand, replicate, or adapt the intervention to a new population or setting. 

A well-defined intervention model: 

• Describes the activities that comprise

the intervention.

• Describes each core component in

detail and identifies the components

that are critical. Each core component

must be specifically described to

ensure it is implemented reliably and

consistently.

• Defines what it means to be a program

participant and what is required to

complete the program. Although each

core component separately may

improve some outcomes, the

completion of all requirements should

ensure the intended outcomes are

achieved for program participants.

• Defines the target population.

This guide is intended to help practitioners to thoroughly describe their intervention 

and communicate the following to potential funders or stakeholders: (1) the 

intervention model as it was designed, (2) the intervention as it is implemented, and 

(3) the parts of the intervention and the population that were evaluated and its

effectiveness. The guide also provides examples (see annotated sidebars) of a welldefined intervention and target population to serve as models of effective descriptions.
2 

Describing the intervention 

A clear description of an intervention includes an explanation of its activities and 

services and details about its core components. Examples include tutoring, 

facilitator-led classes or workshops, one-on-one coaching, case management, 

electronic or telephone communication with participants, and sustaining the capacity 

of the organization implementing it. 

A full description of an intervention must be: 

• Operational. The description must enable a 

component to be taught, learned, and practiced, and 

must promote consistent service delivery. It is 

important to be specific to ensure consistent 

implementation. For example, a component 

described as being offered “regularly” is not 

operational because the information is not specific

enough to provide consistent service across 

locations. 

• Complete. Each core componentmust be 

thoroughly described. A thorough description 

includes: 

o Mode of service delivery, such as face-to-face or electronic communications. 

o Intensity, or how long, how often, and how much of the component each 

participant should receive. For example, a participant might need 2 hours of 

tutoring three times a week for 10 weeks (intensity =60 hours). 

o Workforce needs, including the type of individuals who deliver the 

component, qualifications needed, and staffing arrangements (for example, 

direct services workforce-to-participant caseloads). Workforce includes 

anyone needed for the component’s implementation regardless of whether 

they are paid by the main provider organization, a partner, or another entity

(such as AmeriCorps members). 

o Setting, including location and venue. The location describes the geographic 

region and subregion, and indicates whether the setting is rural or urban. The 

venue describes the place where activities occur, such as a community center, 

home, nonprofit, park, or school. When the intervention is implemented in 

different settings, the description should explain which components occur in 

each setting. For example, job training might happen at a training site, and job 

coaching might happen at both the training site and the workplace. 

The intervention description should also identify who is a participant and what a 

participant must do to complete or graduate from a program. Questions that arise in 

defining a participant might include: (1) Is everyone who enrolls a participant?; and

(2) What is the minimum amount of services or length of time in the program for a 

person to be considered a participant? Examples of completion include, participants 

who finish a course and obtain a certificate, or participants who achieve their desired 

weight loss and maintain it for at least one month. 

EXAMPLE OF AN 

INTERVENTION 

DESCRIPTION

The U.S. Football 

Foundation developed 

the Flag Football for 

Fitness (F4) program 

to combat childhood 

obesity, promote 

healthy eating and 

exercise habits, and 

foster positive youth 

development among

Target 

population

children in grades 

K–8 attending urban 

schools that are 

receiving Title I 

funds. In F4 children 

improve football skills 

in a low -pressure 

environment w hile 

learning about 

important nutritionrelated concepts and 

healthy dietary and 

exercise habits. 

Setting and 

mode

The program 

operates face-to-face 

in a group format at

local schoolsin 

urban school 

districts throughout 

the country.

Intensity

Sessions are 90 

minutes per day, 3 

days a week, for 24 

weeks during the 

school year, 

including a 12-week 

season during the 

fall and a 12-week 

season during the 

spring.

Intervention as 

implemented

About 75 

percent of sites 

offered F4 

programming 3 days 

a week for 12 weeks 

(36 sessions during 

the fall and spring 

seasons). Reasons 

for offering fewer 

sessions included 

school district 

scheduling, weather, 

and lack of daylight.
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EXAMPLE OF AN 

INTERVENTION 

DESCRIPTION

(continued)

Workforce structure:

Workforce 

needs

• Each community 

relies on a site 

coordinator to 

oversee the 

administrative 

and 

programmatic 

functions of F4 in 

their area. Before 

filling the 

position, site 

coordinators 

must have at 

least 5 years of 

experience and 

at least a 

bachelor’s 

degree. 

• Each site has a 

coach with 

demonstrated 

experience 

working with 

youth. 

Individuals 

recruited as F4 

coaches have a 

variety of 

backgrounds and 

most commonly 

are college 

students, 

teachers, school 

workforce , and 

parents.

Describing the target population 

A description of the target population should identify the main characteristics of the 

people it is intended to serve, including risk factors such as age or grade ranges, 

demographics, and others. It is important to be specific. For example, describing a 

population as “at-risk youth” is inadequate because neither at-risk nor youth is 

defined. It would be more specific to describe the population as “youth ages 12–17 

who have been involved with the juvenile justice system.” 

If a program is intended to serve more than one population, 

each must be described with such specificity.

The description of the target population should also include 

eligibility criteria for participation. For example, an adult 

obesity intervention might serve participants ages 18–64 

who have a body-mass index of at least 30, but it may 

exclude all pregnant women. These requirements clearly 

define who can be included or excluded from the 

intervention. 

Distinctions in describing the intervention 

When describing the intervention, note 

any distinctions between these three 

angles: 

1) As designed. The intervention model 

describes the intervention as the 

developer designed it. 

2) As implemented. Although some 

practitioners implement the model 

strictly as it was designed, they could 

implement components in a different 

manner or target a different 

population. These changes may be 

intentional or may be an unintended 

consequence of an event. For 

example, the ratio of case manager to

participant in the intervention design 

might be 1 to 15, but workforce turnover may push it closer to 1 to 25.

3) As evaluated. Often, evaluations designed to show that the intervention 

improves outcomes are conducted only on a subset of the intervention’s 

components or populations. For example, a nationwide after-school program 

focused on health education might tailor curricula differently for boys and girls. 

If a study examined outcomes for girls enrolled in schools that are located in 

large urban areas and offer weak in-school health education programs, the 

evidence of effectiveness could be attributed to those conditions only. The 

intervention may or may not be as effective for boys, for girls in schools that 

offer strong in-school health programs, or in nonurban settings.
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Changes to the intervention model during implementation 

or an evaluation are not necessarily erroneous; indeed, they 

may be intentional or required (because of budget 

constraints, for example). However, funders and other 

stakeholders might question whether such changes will 

affect outcomes. A full description of the intervention or 

population therefore should justify any changes to the 

intervention model and describe why the same (or 

improved) outcomes might be expected.

For example, an organization with case management ratios 

that are higher than in the intervention model could 

highlight how it adopted new technology for virtual meetings that reduced time 

needed for travel and allowed those implementing the intervention to devote more 

time to participants, despite the higher ratios. Likewise, for the evaluation that was 

conducted only for girls in selected schools, the organization should provide 

evidence that the intervention might also be effective for boys, girls in schools with 

strong in-school health programs, or in non-urban areas. The organization would 

then plan accordingly for future evaluations to demonstrate effectiveness along these 

lines.

EXAMPLE OF A 

POPULATION 

DESCRIPTION 

ActivatED is a 

nonprofit 

organization based 

in the San 

Francisco Bay Area. 

Founded in 1996, 

ActivatED serves 

more than 

Population 

and setting as 

defined

65,000 

children annually in 

kindergarten through 

fifth or sixth grades, 

in schools across 

the country. 

Participating schools 

must have at least 50 

percent of students 

eligible for free or 

reduced-price meals. 

To select schools 

for its study sample, 

ActivatED provided 

a list to evaluators 

of 

Population 

and setting as 

ev aluated

all elementary 

schools (119 in total) 

in which ActivatED 

operated full-time 

between 1996 and 

2007 in 11 school 

districts in the San 

Francisco Bay Area. 

All other elementary 

schools (80 in total) 

with at least 50 

percent of students 

eligible for free or 

reduced-price meals 

in the same 11 

school districts were 

selected to serve in a 

comparison group.

Further Reading 

Community Tool Box, Designing Community Interventions

(https://ctb.ku.edu/en/table-of-contents/analyze/where-to-start/designcommunity-interventions/main) 

Home Visiting Evidence of Effectiveness Review, Reporting Guide for Study 

Authors

(https://homvee.acf.hhs.gov/HomVee_Author%20Reporting%20Guide_051116

_B508.pdf)

What Works Clearinghouse Review, Reporting Guide for Study Authors: Group 

Design Studies

(https://ies.ed.gov/ncee/wwc/Docs/ReferenceResources/wwc_gd_guide_022218

.pdf)

About the Series

The Corporation for National and Community Service (CNCS) supports the scaling of effective 

interventions that it funds and has engaged Mathematica Policy Research to conduct the Scaling 

Evidence-Based Models project (contract GS10F0050L/CNSHQ16F0049). As part of that project, 

Mathematica developed a series of guides to help practitioners collect evidence on their 

interventions’ effectiveness and increase the likelihood of successfully scaling those interventions.

Each guide provides a succinct overview of a topic that can help practitioners. The guides are based 

on research and practitioners’ experiences, but they do not provide exhaustive reviews of a topic. 

More in-depth articles can be found in the Further Reading section.