The mathematics department at a university wants to administer a survey to a sample of students. Suppose that 20 faculty members volunteered to administer the survey, and those faculty members who volunteered gave the survey to all students in one course of their choice. This is an example of a cluster sample. Explain what makes this sample biased.
The population here comprises of all the students. So, for a sample to be representative (non biased), the sampling process should give equal importance to all members of the population. Here, when the cluster is chosen, the faculty members picked a particular course to be the cluster to be sampled. The cluster was not randomly chosen and it was based on the choice of the surveyor. So, here selection bias exist as the sample is based on their choice.
Also, non representative bias can exist in the sample because the course chosen might not be representative of the whole population.
The mathematics department at a university wants to administer a survey to a sample of students....
The faculty senate at a large university wanted to know what proportion of the employees thought the food services at the university are satisfactory. The statistics department offered to cooperate in conducting a survey, and a simple random sample of 100 faculty members was selected. A survey form was sent by email to these 100 employees. In this case, the population of interest is: all the employees who are faculty members. all the employees at the university. all the employees...
The faculty senate at a large university wanted to know what proportion of the students thought foreign language classes should be required for everyone. The statistics department offered to cooperate in conducting a survey, and a simple random sample of 500 students was selected from all the students enrolled in statistics classes. A survey form was sent by email to these 500 students. In this case, the sampling frame is: 1. all the student at the university. 2. all the...
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Suppose the math department chair at a large state university wants to estimate the average overall rating, out of five points, that students taking Introductory Statistics gave their lecturers on their end-of-term evaluations. She selects a random sample of 32 evaluations and records the summary statistics shown. Sample size Sample mean Sample standard deviation Population standard deviation Standard error Confidence level ? ?⎯⎯⎯ ? ? ??⎯⎯⎯⎯ ? 32 3.9102 1.0809 1.0213 0.1805 95% The department chair determines the standard error...
Suppose the math department chair at a large state university wants to estimate the average overall rating, out of five points, that students taking Introductory Statistics gave their lecturers on their end-of-term evaluations. She selects a random sample of 36 evaluations and records the summary statistics shown. Sample size Sample mean Sample standard deviation Population standard deviation Standard deviation of ?¯ Confidence level ? ?⎯⎯⎯ ? ? ??⎯⎯⎯⎯ ? 36 3.8711 1.0755 1.0222 0.1704 95% The department chair determines the...
Which of the following situations is not appropriate to use a stratified random sample? when the researcher can representatively sample even the smallest and most inaccessible subgroups in the population when the researchers want to observe existing relationships between 2 or more subgroups when the researcher wants to highlight a specific subgroup within the population when the researcher wants to survey the 20 faculty members in the mathematics department
In the survey of a random sample of students at a university, two questions were, “How many hours per week do you usually study?” and “Have you smoked marijuana in the past six months?” An analysis of the results produced the following SPSS output: A research question of interest is whether students who have smoked marijuana (group Y) in the past 6 months differ in study hours on average per week than those who have not (group N). Which...
The university finance department wants to know if the average age of students at their university is greater than the average for other universities. A random sample of student records is taken from the own university (population 1) and a random selection of student ages from other three universities are taken (population 2). A significance level of 0.05 is chosen. The null and alternative hypotheses are: ?0H_0: ??H_a: The samples are selected, and the results are: ?1 = 28,7 ????? ?1...
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