Exam 7: Sampling and Sampling Distributions

________ results from the exclusion of certain groups of subjects from a population frame.

If the population distribution is skewed, in most cases the sampling distribution of the mean can be approximated by the normal distribution if the samples contain at least 30 observations.

A sampling distribution is defined as the probability distribution of possible sample sizes that can be observed from a given population.

The standard error of the mean

To use the normal distribution to approximate the binomial distribution, we need ________ and ________ to be at least 5.

To demonstrate a sampling method, the instructor in a class picked the first 5 students sitting in the last row of the class. This is an example of a

The standard error of the mean is also known as the standard deviation of the sampling distribution of the sample mean.

TABLE 7-6 According to an article, 19% of the entire population in a developing country have high-speed access to the Internet. Random samples of size 200 are selected from the country's population. -Referring to Table 7-6, among all the random samples of size 200, 90 % will have less than ________ % who have high-speed access to the Internet.

Which of the following types of samples can you use if you want to make valid statistical inferences from a sample to a population?

The professor of a business statistics class wanted to find out the mean amount of time per week her students spent studying for the class. She divided the students into the left, right and center groups according to the location they sat in the class that day. One of these 3 groups was randomly selected and everyone in the group was asked the mean amount of time per week he/she spent studying for the class. This is an example of a cluster sample.

TABLE 7-1 The manager of the customer service division of a major consumer electronics company is interested in determining whether the customers who have purchased a DVD player made by the company over the past 12 months are satisfied with their products. -Referring to Table 7-1, if a customer survey questionnaire is included in all the DVD players made and sold by the company over the past 12 months, this method of collecting data will most like suffer from

The average score of all pro golfers for a particular course has a mean of 70 and a standard deviation of 3.0. Suppose 36 pro golfers played the course today. Find the probability that the average score of the 36 pro golfers exceeded 71.

TABLE 7-4 The lifetimes of a certain brand of light bulbs are known to be normally distributed with a mean of 1,600 hours and a standard deviation of 400 hours. A random sample of 64 of these light bulbs is taken. -Referring to Table 7-4, the probability is 0.20 that the sample mean lifetime differs from the population mean lifetime by at least how many hours?

The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed, with mean of 3.2 pounds and standard deviation of 0.8 pound. What percentage of samples of 4 fish will have sample means between 3.0 and 4.0 pounds?

TABLE 7-5 According to a survey, only 15% of customers who visited the website of a major retail store made a purchase. Random samples of size 50 are selected. -Referring to Table 7-5, the standard deviation of all the sample proportions of customers who will make a purchase after visiting the website is ________.

A telemarketer set the company's computerized dialing system to contact every 25th person listed in the local telephone directory. What sampling method was used?

TABLE 7-7 Online customer service is a key element to successful online retailing. According to a marketing survey, 37.5% of online customers take advantage of the online customer service. Random samples of 200 customers are selected. -Referring to Table 7-7, 90% of the samples proportions symmetrically around the population proportion will have between ________ % and ________ % of the customers who take advantage of online customer service.

TABLE 7-5 According to a survey, only 15% of customers who visited the website of a major retail store made a purchase. Random samples of size 50 are selected. -Referring to Table 7-5, what proportion of the samples will have less than 15% of customers who will make a purchase after visiting the website?

As the sample size increases, the standard error of the mean increases.

Which of the following sampling methods will more likely be susceptible to ethical violation when used to form conclusions about the entire population?