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91Ó°ÊÓ

Suppose a person with access to student records at your college has an alphabetical list of currently enrolled students. The person looks at the records of every 10th person (starting with a randomly selected person among the first 10 ) to see whether they have paid their latest tuition bill. What kind of sampling does this illustrate?

Short Answer

Expert verified
The type of sampling illustrated by this procedure is known as Systematic Sampling.

Step by step solution

01

Understanding the Given Scenario

First, carefully read the given problem. A person is checking not all student records but selecting every 10th person, in alphabetical order, starting from a random person among the first 10. The students are not selected randomly per se, but rather there is a system being followed.
02

Identifying the Sampling Technique

The individual selects 'every 10th person' from an alphabetical list of students. This indicates that the sample is not being randomly or arbitrarily chosen, but rather according to a set pattern (i.e., every 10th person). This method is a type of systematic sampling, where items are ordered and then chosen at regular intervals to be part of the sample.

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Key Concepts

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

Sampling Techniques
When researchers or statisticians need to gather information, they often can't collect data from every individual in a population due to time, cost, or practicality constraints. Thus, they use sampling techniques to select a representative subset of the population which can provide insights into the whole. There are various sampling methods, each with its advantages and specific use cases. Simple Random Sampling is quite straightforward; it ensures that every member of a population has an equal chance of being chosen. Systematic Sampling, which is highlighted in the given exercise, involves selecting members at regular intervals from an ordered list. Stratified Sampling divides the population into subgroups and randomly samples from each subgroup proportionally. Lastly, Cluster Sampling involves dividing the population into clusters and randomly selecting whole clusters for study.

Choosing the right sampling technique is crucial. It affects the quality and accuracy of the data collected, as well as the validity of any conclusions made based on that data.
Simple Random Sampling
Considered one of the most basic and fair sampling methods, Simple Random Sampling ensures that every individual has an equal probability of being selected. This method is akin to drawing names out of a hat. In this method, every possible sample of the desired size has the same chance of being chosen. The benefit of this approach is that it minimizes sampling bias and offers a straightforward process for selection. However, it requires a complete list of the population and can be impractical for large populations. When data are collected using this method, statistical analysis can typically be applied without needing complex formulas, which simplifies the inferential process.
Statistical Sampling
Statistical Sampling refers to the process of selecting a subset of a population to estimate characteristics of the whole population. It's a cornerstone of statistical analysis because it allows for collecting and analyzing data that would be impossible to harness in its entirety. Statistical sampling techniques are used in hypothesis testing, estimating population parameters, and in making predictions about a population from the sample. When executed correctly, statistical sampling can provide reliable results without examining every single case. Key considerations in statistical sampling include the size of the sample, the sampling method used, and potential sources of bias or error in the selection process.
Data Collection Methods
Apart from determining which sampling method to use, deciding on the data collection methods is another critical step in the research process. There are many ways to collect data, including surveys, interviews, questionnaires, observations, and experimentations. The collection method depends largely on the research objective and the nature of the data needed. Quantitative data collection methods involve structured techniques such as online surveys, face-to-face interviews, or systematic observation. Qualitative data collection methods like focus groups or open-ended surveys are better for gathering in-depth insights. Effective data collection methods ensure that the information is accurate, consistent, and reliable, leading to more trustworthy results in statistical analysis.

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Most popular questions from this chapter

When patients are admitted to hospitals, they are sometimes assigned to a single room with one bed and sometimes assigned to a double room, with a roommate. (Some insurance companies will pay only for the less expensive, double rooms.) A researcher was interested in the effect of the type of room on the length of stay in the hospital. Assume that we are not dealing with health issues that require single rooms. Suppose that upon admission to the hospital, the names of patients who would have been assigned a double room were put onto a list and a systematic random sample was taken; every tenth patient who would have been assigned to a double room was part of the experiment. For each participant, a coin was flipped: If it landed heads up, she or he got a double room, and if it landed tails up, a single room. Then the experimenters observed how many days the patients stayed in the hospital and compared the two groups. The experiment ran for two months. Suppose those who stayed in single rooms stayed (on average) one less day, and suppose the difference was significant. a. Can you generalize to others from this experiment? If so, to whom can you generalize, and why can you do it? b. Can you infer causality from this study? Why or why not?

Fish Consumption and Arthritis A 2017 study reported in the Harvard Health Blog investigated the association between fish consumption and disease activity in 176 rheumatoid arthritis patients (Tedeschi et al. 2017). Frequency of fish consumption was assessed through a questionnaire. Researchers found that participants who consumed fish at least two times per week showed significantly lower disease activity (in other words, less inflammation associated with the disease) than participants who consumed never or less than one time per month. Does this study show that fish consumption causes lower disease activity in rheumatoid arthritis patients? Explain.

In a 2018 study, researchers investigated the effect of the drug alteplase in the treatment of stroke patients (Thomalla et al. 2018). Patients were randomly assigned to receive intravenous alteplase or a placebo. The patients' neurological function was assessed 90 days after treatment. Of the 246 patients who received alteplase, 131 had a positive neurological outcome. Of the 244 patients who received a placebo, 102 had a positive neurological outcome. a. Was this an observational study or a controlled experiment? Explain. b. Find the percentage in each group that had a positive neurological outcome 90 days after treatment. c. Researchers performed a test to determine if there was a significant difference in the proportion of positive neurological outcomes between the treatment and control groups. The p-value for the test is \(0.003 .\) Based on a \(0.05\) significance level, choose the correct conclusion: i. Researchers have shown that alteplase may be an effective treatment for stroke patients. ii. Researchers have not shown that alteplase may be an effective treatment for stroke patients.

In a 2018 study reported in The New England Journal of Medicine, Johnston et al. studied the effect of a combination of the drug clopidogrel and aspirin on reducing the rate of recurrent stroke among stroke patients. Stroke patients in the study were randomly assigned to receive clopidogrel and aspirin \((n=2432)\) or a placebo and aspirin \((n=2449) .\) Of those receiving clopidogrel and aspirin, 121 had another stroke. Of those receiving the placebo and aspirin, 159 had another stroke. Researchers concluded that patients with minor ischemic stroke or high-risk TIA who received a combination of clopidogrel and aspirin had a lower risk of having another stroke. a. Compare the percentage in each group who had another stroke. Based on these percentages, does it seem like clopidogrel might be effective in reducing the risk of recurrent stroke? b. Was this a controlled experiment or an observational study? c. Identify the treatment and response variables. d. State the conclusion in terms of cause and effect or explain why cause-and- effect conclusions cannot be drawn from this study.

Evaluate the study based on the extracts from the study abstracts by answering the following questions: a. What is the research question that the investigators are trying the answer? b. What is their answer to the research question? c. What were the methods they used to collect data? d. Is the conclusion appropriate for the methods used to collect data? e. To what population do the conclusions apply? f. Have the results been replicated (reproduced) in other articles? What Would Batman Do? Researchers have found that psychological distance from our current situation facilitates selfcontrol and allows individuals to transcend urgencies of a situation by taking a more distanced perspective. Executive function refers to higher-order regulatory processes such as inhibition and working memory. In this study published in the journal Developmental Science, researchers investigated the relationship between psychological distance and executive function in pre-school children (White and Carlson 2015). Read the following excerpts from the study abstract and evaluate the study using the given questions. Method: Three-year old \((n=48)\) and 5 -year old \((n=48)\) children were randomly assigned to one of four manipulations of distance from self and asked to perform several tasks that assessed executive function (EF). The four groups were: 1 ) self-immersed, in which children were told to focus on what they are thinking and how they feel when the task got hard, 2) Third person, in which children were told to talk to themselves using their own name when the task got hard, 3) Exemplar, in which children were told to pretend they were someone else who would be really good at the task, like Batman, Dora the Explorer, Bob the Builder, or Rapunzel, and the children put on costume props before completing the task, and 4) a control group, in which children were given no instruction regarding distance from self before performing the task. Results: Five-year-olds benefited from taking a self-distanced perspective on an executive function task through third person self-talk as well as taking the perspective of an exemplar other, such as Batman. Three-year-olds did not show increased EF performance as a function of greater distance from self. Conclusion: The current study revealed the power of self-distancing to facilitate reflective, goal-directed action in the context of a cool EF task for young children. Children's ability to improve EF by mentally transcending their context underscores the critical role that representational capacities play in the development of self-control.

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