2301 Final Exam Workbook Essay

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.

3) Describe in your own words (do not directly quote any source) the difference between the distribution of a sample and the sampling distribution. Use an example in which the original population has a binomial distribution. You will probably use concepts from the book or another source, so be sure to cite any concepts that come from such sources (even if you paraphrase).

Explain how you would enforce the data constraint that HW7G_ORDER_ITEM.UnitPrice be equal to HW7G_SERVICE.UnitPrice, where HW7G_ORDER_ITEM.Service = HW7G_SERVICE.Service. Again, no code at this time, just an explanation.

Two important sleep restriction studies that also included a short in-laboratory recovery phase were those by Dinges and colleagues11 and Belenky and colleagues.4 In the former study, sleep was restricted 33% below habitual sleep duration (average 4.98, SD 0.57 per night) for seven consecutive nights, after which participants were allowed one or two 10 hour recovery sleeps.11 In the latter, participants were permitted either 3, 5, 7 or 9 hours in bed each night, for seven nights, followed by three 8 hour recovery opportunities.4 These studies show that either two 10 hour or three 8 hour sleep opportunities were sufficient to recover performance to baseline levels. Although, participants felt that their functioning was restored with subjective reports of sleepiness and performance recovering to baseline; indicating that subjective measures do not appear to accurately parallel objective measures of neurobehavioural recovery. These findings suggest that more than 2 or 3 nights of extended sleep may be needed to return neurobehavioral functions to baseline levels. This may be especially important in situations where individuals are not able to choose or extend the length of their recovery sleep

Describe the sample. How does this sample represent the population? What makes a sample strong or weak? Evaluate this sample.

I chose (c) for the answer as I thought that since both schools took the same percentage size of about 3% of the undergraduates and both had a proportion, p= 0.80, Johns Hopkins and Ohio State would have almost the same sampling variability. I forgot to take into account that each school had different numbers of undergraduates. However, the correct answer is (b). Since a simple random sample of about 3% of Ohio State is about (0.03 x 40,00) = 1,200, it has a larger sample than the (0.03 x 2,000) = 60 undergraduates that make up the simple random sample of about 3% of the undergraduates at Johns Hopkin, meaning Ohio State has smaller variability. Thus, the estimate from Johns Hopkins has more sampling variability than that from Ohio State since it has a smaller sample of 60 undergraduates, making

When conducting a study, it is impossible to collect data from the whole population, therefore it is important to select a representative sample because sampling makes it possible to select a representative for study and discover things that apply to many more people who are not studies (Maxfield & Babbie, 2012). The purpose of sampling is to generate a set of individuals or other entitles that give us a valid picture of all such individual or other entitles. It is important to generalise from a sample to unobserved population the sample in intended to represent. Therefore, when selecting a group of subjects for study, it is important to ensure that we represent some larger population.

You plan to draw a sample of 60 students. Which of the following procedures will give you a simple random sample A) You assume that students have been randomly placed in classes, so you choose three classes by random selection and place all of those students in your sample. B) You have a list with the names of all the students on it. You choose one out of the first 10 names at random. Then you choose every nth student name on the list until you have 60 students for your sample. C) Choose the first 60 students that pass through the front door at the beginning of school in the morning. D) Put the name of each classmate in school on a piece of paper and place the pieces of paper in a cardboard box. Next randomly select 60 pieces of paper from the box. E) You randomly choose 10 students from each of

Sampling is the process of selecting a representative group from the population in order to make an inference about the population and use to represent the population. In this case, Santa Fe Grill should employed probability sample to meet the qualitative requirement of being unbiased and it allows them to draw statistical inference. Probability sample is widely used in conducting marketing research since everyone in the population gets an equal opportunity to be a part of the representative sample.

The project will be a multi-year phased approach to have all sites (except JV and SA) on the same hardware and software platforms.

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

In this study, it uses surveys to analyze 135 seabirds to find that today about 90 seabirds have traces of plastic in their stomachs. A survey is what allows us to ask/study large numbers or people (in this case seabirds) questions about attitude and behavior (textbook p.44). The sample size for this specific study would be 135 which is the subset of a population being studied. The population in this case would be all seabirds, which is the entire group from which the sample was taken

Through what means would you extract a representative sample from the total population? Describe your procedure.

a. The way you can gain access to the Official SAT Question of the Day is

All of these examples of collecting and conducting data will have to involve using samples conducted by the population and applying inferential information, which is obtained through representatives. These samples are typically those possessed by the population of interest when conducting a sample population by choosing random samples of every different sample size. It gives them an equal chance of selection and does not target those that would compromise the data.