Statistics Chapter 7 Homework Essays

12. _____ For a given population, confidence intervals constructed from larger samples tend to be narrower than those constructed from smaller samples. Which statement below best describes why this is true? (A) The variability of the sample mean is less for larger samples. (B) The z-value for larger samples tends to be more accurate. (C) The population variance is larger for large populations. (D) As the sample size increases, the z-value (or t-value) becomes smaller. A machine dispenses potato chips into bags that are advertised as containing one pound of product. To be on the safe side, the machine is supposed to be calibrated to dispense 16.07 ounces per bag, and from long time observation, the distribution of the fill-weights is known to be approximately normal and the process is known to have a standard deviation of 0.15 ounces.

a) Based on a randomly selected group of 500 patients with high cholesterol, it was found that 67% have heart disease. Is this a population or a sample; explain your answer. Raw data is collected from a subset of patient with high cholesterol to determine numbers describing characteristics of the subset (Bennett, Briggis, & Triola, 2009). The raw data collected from the 500 patients is consolidated and summarized to form sample statistics. The raw data and sample statistics are indications that this is a sample (Bennett, Briggis, & Triola, 2009).

Discuss the sample. What was the sampling method used? How was the sample selected? What is the sample size? Is the size adequate? How do size and method of selection influence the results, i.e., random sampling, stratified sampling, etc.

The central limit theorum states that the average of a distribution will be normal regardless of distribution unless the parent distribution is missing data. Simple random sampling is a form of sampling where the total sample group consists of N objects and the sample taken consists of n objects resulting in a predictable result. The sample mean of a random sampling would be within the resulting confines of the sample group. In a population of 20 people, there were 15 donars, but the average gift was well below the per-capita income. However, there were a minority of large donors that far exceeded the per-capita income causing the mean to be much higher than expected.

What proportion of a normal distribution is located between the mean and z = 1.40?

Consider the following question: someone takes a sample from a population and finds both the sample mean and the sample standard deviation. What can he learn from this sample mean about the population mean?

A. Sampling is a selection of a smaller percentage of individuals from within a larger population that is used to estimate the attitudes and characteristics of the whole population. Sampling saves time and money which is always a good thing, and allows for more manageable research. It may be almost impossible to identify every member of a population/group some may be too large, for example, if you were conducting a study on high school students as to whether they bring lunch to school or eat at the cafeteria, and this research was conducted for the entire state of Texas. Well, it would take an enormous amount of manpower and money to survey every single high school student in the state plus you would have other factors to consider as well. Then you would run into managing issues with such a large endeavor, so choosing a sample or small representation of individuals from the larger population is more

A) The sample is the 100 students that took the survey and the population are the students at the school.

Answer: The binomial distribution also known as Bernoulli distribution is a discrete probability distribution of the number of successes in a sequence of n independent true or false experiment of which they individually yield success with probability p. (Wikipedia, n.d.)

Random Sample: A random sample is one that fairly represents a population, as each member has an equal chance of being included. Random sampling isn’t used in Dr. Tabors research. She wished to investigate the relationship between alertness and sleep in university students, but only gave her survey to 150 freshmen in her psychology class. Each member of a university was not given an equal chance of being included in the survey, and thus isn’t a random sample. The sample that she selected would be unrepresentative of an entire American university student body.

distribution occurs so much. It is also a good way to calculate the collection of data with minimal

Researchers need to select individuals who are part of the population for their studies. That is, from all possible people or organizations in the population, they select a sample for study from the population. A sample is a subgroup of the population that the researcher plans to study for generalizing about the population (Plano-Clark & Creswell,

A sample is used when a portion of the target population must be used; neither time nor money allows the entire population to be used. A census would be the other form of data collection because the entire population is used. The portion used in the sample must be carefully selected to represent that population. If sampling is chosen, the researcher must determine which and how many people to interview, which and how many events to observe, or which and how many records to inspect (Cooper, 2014, p. 112). Choosing which sample method to be used is very important because this will be the basis for the way data is collected. If the wrong sample method is chosen the data will not be accurate, and in turn the analysis and the outcome will also be incorrect. For the purpose of this research, BP will use probability method; this is the best method to use because it will give you the most powerful statistical analyses on the results ("choosing a sampling method," 2013, para. 1). The sampling frame within the probability method used will be stratified sampling. Even though

How did you select this research study? What search terms did you use? What database did you use? What was your rationale for selecting this particular study to analyze over the others in the search results? What is the full reference in APA format?

Sampling means take one typical part of from the whole population, which is an essential method for corporations to get the result of their new products or policies. When corporations test the sample, they do not actually need the specific data and number. In addition, the total number of comprising the population is usually large, so the corporations usually do not test the whole population for reducing meaningless time and labor cost. Sampling is a good way to trade effectiveness to efficiency. Thus, the results of sampling are always directly connected with and also affected the applying or changing of products and polices of corporations.