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. 2. Objectives. To define what dosage contributes to an evaluation designTo identify at least one indicator that measures dosage in prevention programsTo choose two strategies for collecting measures of dosage. . 3. What Does Dosage Add to an Evaluation?. Dosage reflects the amount of the interve
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1. Accounting for Dosage for Prevention Grantees Renate M. Houts, Ph.D.
RTI International
Presented at OAPP National Care and Prevention Conference
December 9, 2008
2. 2 Objectives To define what dosage contributes to an evaluation design
To identify at least one indicator that measures dosage in prevention programs
To choose two strategies for collecting measures of dosage
3. 3 What Does Dosage Add to an Evaluation? Dosage reflects the amount of the intervention that is offered to and received by participants
Dosage is related to treatment fidelity
Dosage helps answer the question of “how much” of the intervention is needed to see an effect
Dosage information can help explain both positive and negative results
4. What Is Dosage? When you go to the doctor and receive a prescription, it has four key components:
Description of treatment: Amoxicillin
Amount of treatment: 250 mg
Frequency of exposure: 2 times per day
Duration of treatment: 10 days
A complete description of dosage involves all four components!
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5. 5 Components of Dosage: Description The description component of dosage answers the “What?” question
What are participants offered?
What do participants receive?
Description needs to be as specific as possible
What is offered and what is received may vary
Some providers may be more engaging than others
Some providers may not cover all of the intended material
Some participants may be more engaged than others
6. 6 Components of Dosage: Amount The amount component of dosage answers the “How much?” question
How much of the intervention did participants receive?
Amount refers to length of intervention
Amount may vary across program components
30 minutes of classroom intervention
30 minutes of after-school intervention
Amount may vary across participants
Participants may arrive late or leave early
7. 7 Components of Dosage: Frequency The frequency component of dosage answers the “How often?” question
How often do participants receive the intervention?
Frequency is typically documented in the following terms:
Number of times given per time frame (e.g., 3 times per month)
Frequency may vary across program components
3 times per week for classroom intervention
2 times per week for after-school intervention
Frequency may vary across participants
8. 8 Components of Dosage: Duration The duration component of dosage answers the “How long?” question
How long do participants receive the intervention?
Duration refers to entire length of the intervention
Duration may vary across different components of the intervention
5 weeks of classroom intervention
3 weeks of after-school intervention
Duration may vary across participants
Dropouts would have shorter durations than others
9. What Does a Complete Dosage Description Look Like? 9 Participant A received “description” “amount,” “frequency” for “duration” Participant A received a lecture for 30 minutes, 3 times per week for 5 weeks