Sampling and Estimation

12 questions

1. 1. Which of the following would be most likely to produce selection bias in a survey?
   Only receiving responses from half of the people in the sample. Conducting interviews by telephone instead of in person. Using a random sample of students at a university to estimate the proportion of people who think that the work experience requirement to become a CFA charterholder should be reduced.
2. 2. For a random sample of 9 portfolio managers, the average portfolio returns are x = 36%, and the sample standard deviation is s = 5%. The standard error of the sample mean is:
   0.557 0.745 1.667
3. 3. Which of the following is least accurate about the standard error of a statistic?
   The standard error measures, roughly, the average difference between the statistic and the population parameter. The standard error can never be a negative number. The standard error increases as the sample size(s) increases
4. 4. A sampling distribution is the probability distribution for which one of the following:
   A sample A sample statistic A population parameter
5. 5. Which statement is not true about confidence intervals?
   A confidence interval is an interval of values computed from sample data that is likely to include the true population value. A confidence interval between 20% and 40% means that the population proportion lies between 20% and 40%. A 99% confidence interval procedure has a higher probability of producing intervals that will include the population parameter than a 95% confidence interval procedure.
6. 6. A randomly selected sample of 400 students at a university with 15-week semesters was asked whether or not they think the semester should be shortened to 14 weeks (with longer classes). Forty six percent (46%) of the 400 students surveyed answered 'yes'. Which one of the following statements about the number 46% is correct?
   It is a sample statistic. It is a population parameter. It is a standard error.
7. 7. Assuming a large sample size, what can be said about the sampling distribution of a positively skewed population?
   The sampling distribution will be positively skewedThe sampling distribution will be normally distributedThe standard deviation of sampling distribution will be equal to the standard deviation of population
8. 8. According to the central limit theorem, which of the following is not important for the sample mean to be close to normal distribution?
   Sample must be largeRandom variables are drawn independentlyPopulation follows normal distribution
9. 9. Which of the following is the appropriate test statistic to use when we have a sample from a nonnormal distribution with known variance and the sample size is large?
   z-statistict-statisticNo test statistic available
10. 10. Which of the following is the appropriate test statistic to use when we have a sample from a normal distribution with unknown variance and the sample size is small?
    z-statistict-statisticNo test statistic available
11. 11. A random sample of 100 investors was taken. It was found that the average returns of this sample were 12%. Assuming normal distribution, and a population standard deviation of 20%, the 95% confidence interval for the population mean will be:
    8.08% to 15.92%8.64 to 15.367.34% to 16.66%
12. 12. Which of the following is not a property of Student's t Distribution?
    Its shape is characterized by the degrees of freedom.As the sample size increases, it approaches the normal distribution.It is non-symmetric