91Ó°ÊÓ

Refer to a study on the effectiveness of an HPV (human papilloma virus) vaccine conducted between October 1998 and November 1999. HPV is the most common sexually transmitted infection-more than 20 million Americans are infected with HPV-but most HPV infections are benign, and in most cases infected individuals are not even aware they are infected. (On the other hand, some HPV infections can lead to cervical cancer in women.) The researchers recruited 2392 women from 16 different centers across the United States to participate in the study through advertisements on college campuses and in the surrounding communities. To be eligible to participate in the study, the subjects had to meet the following criteria: (1) be a female between 16 and 23 years of age, (2) not be pregnant, (3) have no prior abnormal Pap smears, and (4) report to have had sexual relations with no more than five men. At each center, half of the participants were randomly selected to receive the HPV vaccine, and the other half received a placebo injection. After 17.4 months, the incidence of HPV infection was 3.8 per 100 woman-years at risk in the placebo group and 0 per 100 woman-years at risk in the vaccine group. In addition, all nine cases of HPV-related cervical precancerous growths occurred among the placebo recipients. [Source: New England Journal of Medicine, \(347,\) no. 21 (November 21,2002\(): 1645-1651\). (a) Describe the sample for the study. (b) Was the sample chosen using random sampling? Explain.

Step by step solution

01

Describing the Study Sample

The study sample consists of 2392 women recruited from 16 different centers across the United States through advertisements on college campuses and nearby communities. The eligibility criteria to participate were: (1) being a female between the ages of 16 and 23, (2) not being pregnant, (3) having no history of abnormal Pap smears, and (4) reporting to have had sexual relations with no more than five men.

02

Assessing the Randomness of the Sample

The sample itself was not chosen using random sampling as it involved voluntary response through advertisements and had specific eligibility criteria. However, random allocation was used to assign the participants to either the vaccine group or the placebo group, ensuring the participants in each group were chosen randomly from the eligible volunteers.

Unlock Step-by-Step Solutions & Ace Your Exams!

• Full Textbook Solutions

  Get detailed explanations and key concepts

• Unlimited Al creation

  Al flashcards, explanations, exams and more...

• Ads-free access

  To over 500 millions flashcards

• Money-back guarantee

  We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Random Sampling

Random sampling is a fundamental technique used in scientific research to obtain a representative subset of a population. In the context of the mentioned HPV vaccine study, it's essential to distinguish between the recruitment of the study participants and how the treatment was assigned to them.

The study recruited participants through advertisements, targeting females aged 16-23 who met certain health criteria. This method does not constitute random sampling because it relies on self-selection; those who saw the advertisements and felt compelled to volunteer may differ from those who did not, leading to potential biases. For a study sample to be truly random, every individual in the target population should have an equal chance of being selected, which is not the case here.

However, once the participants had been recruited, random allocation was employed to divide them into two groups: one for the HPV vaccine and the other for the placebo. This step is crucial because it minimizes selection bias within the study, helping to ensure that the differences in outcomes between the two groups can be attributed as much as possible to the vaccine itself, rather than to pre-existing differences between the participants.

Study Sample Description

The accuracy of public health research heavily relies on a clear and thorough description of the study sample. In the HPV vaccine study, the sample description is detailed, specifying that the participants were 2392 young women across 16 different centers in the U.S.

Specifically, the inclusion criteria were defined by age, pregnancy status, health history, and number of sexual partners. These criteria were designed to select a group of individuals who would most likely benefit from an HPV vaccine—those at an increased risk for HPV infection but not already affected by factors that could undermine the vaccine’s potential efficacy.

It's vital for such research to have a well-characterized sample description like this because it enables other researchers to understand the context of the study, compare it with other studies, and replicate it if necessary. Moreover, when the target population is accurately represented in the sample, the findings can be generalized with more confidence to the wider population.

Public Health Research

The study of the HPV vaccine's effectiveness is a prime example of public health research, which is conducted to understand health-related conditions and to develop strategies for improving the health of populations.

Such research addresses questions about the incidence and prevalence of diseases, the effectiveness of interventions, and the overall impact on society. The HPV vaccine study specifically aimed to determine the vaccine’s efficacy in preventing infections and related cervical precancerous growths—a critical concern in reproductive health.

To disseminate valid findings, public health studies must use rigorous methodologies, including sound sampling techniques, comprehensive sample descriptions, and appropriate statistical analyses. Transparent reporting allows the wider public health community to evaluate the reliability of the study, apply its findings to policy-making, and inform healthcare providers and patients about preventive practices like vaccination. Ultimately, this contributes to the broader goal of public health research: to protect and improve the health of entire populations through evidence-based strategies.