91Ó°ÊÓ

Multiple choice: Emotional health survey \(\quad\) An Internet poll conducted in the United Kingdom by Netdoctor. co.uk asked individuals to respond to an "emotional health survey" (see www.hfienberg.com/clips/pollspiked. htm). There were 400 volunteer respondents. Based on the results, the British Broadcasting Corporation \((\mathrm{BBC})\) reported that "Britons are miserable-it's official." This conclusion reflected the poll responses, of which one quarter feared a "hopeless future," one in three felt "downright miserable," and nearly one in ten thought "their death would make things better for others." Which of the following is not correct about why these results may be misleading? a. Many people who access a medical Web site and are willing to take the time to answer this questionnaire may be having emotional health problems. b. Some respondents may not have been truthful or may have been Internet surfers who take pleasure in filling out a questionnaire multiple times with extreme answers. c. The sample is a volunteer sample rather than a random sample. d. It's impossible to learn useful results about a population from a sample of only 400 people.

Step by step solution

01

Understand the Question

We are asked to identify the statement that is NOT correct regarding why the results of the Internet emotional health survey may be misleading. This means we need to find the statement that does not serve as a valid criticism of the survey's methodology or results interpretation.

02

Analyze Statement a

Statement a suggests that the results may be misleading because individuals accessing a medical website who volunteer to answer a questionnaire might already have emotional health issues. This could bias the results as these individuals do not represent the general population.

03

Analyze Statement b

Statement b posits the possibility that respondents might not be truthful, possibly due to malicious intent or as a joke, and that some might complete the survey multiple times with extreme answers. This could lead to misleading results as the data wouldn't accurately reflect genuine responses.

04

Analyze Statement c

Statement c points out that the survey results are based on a volunteer sample rather than a random sample. Volunteer samples can result in biased data because individuals self-select their participation, often leading to non-representative samples of the population.

05

Analyze Statement d

Statement d claims that it is impossible to obtain useful results about a population from a sample of only 400 people. This is incorrect because, in statistical practice, valid inferences can often be made from samples as small as 400 if the sampling process is well-designed and random.

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.

Understanding Volunteer Samples

A volunteer sample involves individuals who choose to participate in a survey or study on their own volition. This type of sampling often lacks randomization, which is crucial in avoiding bias. When people volunteer for a study, it means they have some interest or stake in the survey topic. For instance, in the Internet poll conducted by Netdoctor in the UK, individuals visiting a medical website and taking time to answer an emotional health survey voluntarily may already have underlying emotional health issues. This can lead to biased results since these respondents are not representative of the general population.

Volunteer samples can be skewed because:

• Participants self-select based on interest or relevance, not at random.
• The sample may over-represent a certain group more interested in the topic.
• The results may not be generalizable to a wider population.

Recognizing these potential biases is crucial when interpreting results from volunteer samples.

Principles of Survey Methodology

Survey methodology is the study of sampling techniques, survey creation, and data collection methods used to collect data from a real-world population. An effective survey methodology ensures that the collected data accurately reflects the intended population. A key aspect in survey methodology is using random samples instead of volunteer samples. Random sampling aims to select participants from a population entirely by chance, helping to ensure every member has an equal opportunity to be chosen.

Good survey methodology involves:

• Careful design of survey questions to avoid leading or loaded questions.
• Establishing a clear, unbiased method for participant selection.
• Testing the survey process through pilots to identify potential problems.

Attention to these details helps in obtaining reliable and valid results, leading to accurate conclusions.

The Importance of Population Inference

Population inference is about making conclusions or generalizations about a population based on data obtained from a sample. For the inference to be valid, the sample must be representative of the broader population. In the Netdoctor's Internet poll, the sample consisted of 400 individuals who volunteered, which compromised its representativeness due to self-selection bias. This makes it difficult to infer the emotional state of the entire British population accurately.

Reliable population inference depends on:

• Ensuring samples are random and representative to reduce bias.
• Using appropriate sample sizes to ensure statistical power and precision.
• Analyzing and interpreting the data carefully to prevent overgeneralization.

Upholding these principles helps in drawing valid conclusions that reflect the true characteristics and opinions of the entire population.