::jj:: DEscanTIvE STATISTICS Identifying and reducing statistical bias I::| l:| |:;. 0.3 V The CEO or a company with 3200 employees wants to study how many of the company's employees suffer from depression. He takes a random samp|_e of 18 employees and meets with them in his office one at a time. There, he asks them this question. Do you suffer from depression? Of the sampled employees, 6% said that they suffer from depression, and the rest said that they don't. (a) Identify and describe the most prominent source of bias in the CEO'S study. r.) _ X 5) Choose the best answer from the ch0Ices below. 0 "he bias comes from the sampling done in the study. The CEO only sampled from employees at the company, so the sample is a sample of convenience. 0 "he bias comes from the phrasmg of the question and the context in which it is asked. Employees at the company are unlikely to respond to the CEO's question truthfully. 0 "he bias comes from having too many of the sampled employees not respond to the question. These employees might answer the question differently than those who did. 0 "he bias comes from the fact that the employees were not allowed to voluntarily choose to be in the sample. Volunteers are more likely to have characteristics that reect the population as a whole. 0 "here is no or very little bias in the CEO's study. The sample size is smaller than 30. Samples of this size are very unlikely to have outliers, meaning that the sample will have characteristics that reect the population as a whole. DESCRIPTIVE STATIST ' 5 Identifying and reducing statistical bias V ilcely to have outliers, meaning that the sample will have characteristics that reect the population as a whole. (b) Describe something the CEO could have done to reduce the most prominent source of bias in the study. Choose the best answer from the choices below. 0 Make sure that the employees could answer the question anonymously, and consider changing the phrasing of the question so that employees would be more likely to answer truthfully. 0 Offer a small raise to the employees in the sample for answering the question. This way the number of employees not responding would be decreased. 0 Use the company HR portal to set up a poll where the employees can choose to answer the question. This way the CEO makes sure the respondents are volunteers. 0 Modify the study to also include the company's customer base in the sample. This way the sample is no longer a sample of convenience. 0 As the sample size is sufficiently small, the study has no or very little bias. So, there is nothing the CED needed to have done to reduce bias