Questions and Answers of Essentials Of Statistics

Compute the median sales for all three toys.
Suppose you are working with a data set that has some very "different" (much larger or much smaller than the rest of the data) scores. What measure of central tendency would you use and why?
As the head of public health, you conduct a weekly census across age-groups of the number of cases of flu reported in your area. By hand, compute the mean and the median by week. Which do you think,
Why is the range the most convenient measure of dispersion yet the most imprecise measure of variability? When would you use the range?
Compute the exclusive and inclusive ranges for the following items. High Score Low Score Inclusive Range Exclusive Range 7 6 89 45 34 17 15 2 1 1
For the following set of scores, compute the range, the unbiased and the biased standard deviation, and the variance. Do these computations by hand. 31, 42, 35, 55, 54, 34, 25, 44, 35
For the following set of achievement scores, compute the unbiased standard deviation and variance. 87, 87, 58, 78, 98, 69, 88, 71, 86, 91
Now compute the biased estimates for the data in Question 4.Data From Question 4 4. For the following set of achievement scores, compute the unbi- ased standard deviation and variance. (Hint: Use
Why are the unbiased estimates computed in Question 4 larger than the biased estimates computed in question 5?Data From Question 4Data From Question 5 4. For the following set of achievement scores,
This practice problem uses the data contained in the file named. There are two variables in this data set.Using Excel, compute the standard deviation and variance (both biased and unbiased) for
You're one of the outstanding young strategists for Big Boy Airlines and are really curious to compare the number of passengers flying in the mornings versus the evenings out of the Kansas City,
You are conducting an experiment on the effectiveness of a reading intervention with young children and want to report the descriptive results to your colleagues. Some of the children received the
Why would you chose to report the variance of a set of scores rather than the standard deviation?
A data set of 50 comprehension scores (Comp Score). Complete the tasks and answer the questions below.a. Create a frequency distribution and a histogram for the set.b. Why did you select the class
What kind of chart would you use to illustrate the following data?a. The number of students in a school district over a period of 10 yearsb. The proportion of 9th, 10th, and 11 th graders who
For each of the following, indicate whether you would use a pie, line, or bar/column chart and explain why.a. The proportion of freshmen, sophomores, juniors, and seniors in a particular universityb.
Go to the library and find a journal article in your area of interest that contains empirical data but does not contain any visual representation of them. Use the data to create a chart. Be sure to
Create a simple column chart that graphs the sales of an ice cream shop over the summer, fall, winter, and spring seasons. If you can, use an ice cream cone for the column. Now, see if you can easily
Create the worst-looking chart that you can, crowded with chart and font junk. If it's worse than your study buddy's chart, you win.
Create a simple bar chart for number of faculty at different ranks (assistant, associate, and full professor) and label the data sets and include axes and chart titles, minor and major vertical grid
1 . Use these data to answer Questions 1.a. Compute the Pearson product-moment correlation coefficient by hand and show all your work.b. Construct a scatterplot for these 10 values by hand. Based on
Use these data to answer Questions 2a and 2b.a. Using either a calculator or Excel, compute the Pearson correlation coefficient.b. Interpret the relationship between these variables using the
Compute the correlation coefficient for the data below, saved, and interpret the coefficient. We are examining the relationship between the number of years· of training that doctors have and their
Height and weight in humans tend to be correlated because they are the result of lots of similar experiences in an individual's life and the person's genetic traits. Name two variables that may not
Data Analysis tools to compute the correlations between hand-washing efficiency scored on a scale of 1 to 5 with 1 being best (Wash), number of times hands are washed each day (Number), and number of
The coefficient of determination between two variables is .64. Answer the following questions:a. What is the Pearson correlation coefficient?b. How strong is the relationship?c. How much of the
Look back at Table 5.3. What type of correlation coefficient would you use to examine the relationship between ethnicity (defined as different categories) and political affiliation (defined as
When variables are related to each other, why might this be the case? And, when two variables are strongly related to one another, does it mean that a change in one causes a change in the other? Why
You're the director of the local health clinic, and you and the city's school district are conducting a study to examine the relationship between school dropout rate and teenage pregnancy. One of the
For the following set of scores, calculate the Pearson correlation coefficient and interpret the outcome. Budget Increase Number of Clients Served 7% 3% 11% 14% 5% 13% 7% 26% 2% 8%
Rank the following correlation coefficients on strength of their relationship (list the weakest first): +.71 +.36 -.45 +.47 -.62
How do you explain the observation that if parents wave garlic over an infant's crib, the child is likely to begin walking between 18 and 24 months of age? These two events are closely correlated!
Go to the library and find five journal articles in your area of interest in which reliability and validity data are reported. Discuss the outcome measures that are used. Identify the type of
Provide an example of when you would want to establish test-retest reliability and when you would want parallel forms reliability.
Here are the test scores for a group of 15 adults who were assessed on their long-term memory in June and again in August using the same instrument. What type of reliability measure would you use to
The observational data between two judges across 50 days of rating. Would you substitute one judge for the other? Why or why not?
How can a test be reliable and not valid? And why is a test not valid unless it is reliable?
When you are testing any experimental hypothesis, why is it important that the test you use to measure the outcome be both reliable and valid?
Describe the difference between the two types of criterion validity and provide an example of each.
Why is construct validity often so difficult to establish?
Go to the library and select five empirical research articles (those that contain actual data) from your area of interest. For each one, list the following:a. What is the null hypothesis (implied or
While you're at the library, select two other articles from an area in which you are interested and write a brief description of the sample and how it was selected from the population. Be sure to
For the following research questions, create one null hypothesis, one directional research hypothesis, and one nondirectional research hypothesis.a. What are the effects of attention span on
Go back to the five hypotheses that you found in question 1 above and evaluate each using the five criteria that were discussed at the end of the chapter.
What kinds of problems might using a poorly written or ambiguous research hypothesis introduce?
What is the null hypothesis, and what is one of its important purposes? How does it differ from the research hypothesis?
What is chance in the context of a research hypothesis? And what do we do about chance in our experiments? .
Why does the null hypothesis presume no relationship between variables?
Time to be even more creative! Provide one null and one research hypothesis and an equation concerning each of the following:a. The amount of money spent on food by undergraduate studentathletes and
Answer the following questions about normal curves:a. What are the characteristics of the normal curve?b. What human behavior, trait, or characteristic can you think of that is distributed normally?
Why is a z score a standard score, and why can z scores be used to compare scores from different distributions with one another?
What is the primary value of using z scores? Provide an example of how they might be used.
Compute the z scores for the following raw scores where X = 50 and the standard deviation = 5. a. 55 b. 50 c. 60 d. 58.5 e. 46
Given a z score of 1.5, a mean of 40, and a standard deviation of 5, what is the corresponding raw score? What is the corresponding t score?
Questions 6a through 6d are based on a distribution of scores with X = 75 and standard deviation = 6.38. Draw a small picture to help you see what's required.a. What is the probability of a score
Using the NORM.S.DIST function, compute the probability that a score would fall between+ 1 and +2 z scores. Remember, you don't need any raw score values because a z score of 1 is a z score of 1 is a
Jake needs to score in the top 10% on a fitness test in order to earn a physical fitness certificate. The class mean is 78, and the standard deviation is 5.5. What raw score does he need to get that
What is the value of understanding the central Limit theorem?
Why doesn't it make sense to simply combine, for example, test grades across different courses- just take an average and call it a day?
Who is the better student, relative to his or her classmates? Here's all the information you ever wanted to know. Math Class Mean Class Standard Deviation 81 2 Reading Class Mean 87 Class Standard 10
And, last but not least, our favorite fun questions: Why is there always a chance for rain (even if the sky is sunny and the forecast is clear)? And why is the only time there is a 100% chance of
Why is significance an important construct in the study and use of inferential statistics?
What's wrong with the following statements?a. A Type I error of .05 means that in 5 out of 100 tests of the research hypothesis, I will reject a true null hypothesis.b. lt is possible to set the Type
What does chance have to do with the testing of the research hypothesis for significance?
Given the following information, would your decision be to reject or fail to reject the null hypothesis? (Set the level of significance at .05 for decision making.) Provide an explanation for your
Why is it "harder" to find a significant outcome (all other things being equal) when the research hypothesis is being tested at the .01 rather than the .05 level of significance?
Why should we think in terms of "failing to reject" the null rather than just accepting it?
What does the actual critical value represent?
What does the obtained value represent?
In Figure 9.2, there is a striped area in the right-hand part of the curve.a. What does that area represent?b. If you tested the research hypothesis at a more rigorous level (say at .01 rather than
When is it appropriate to use the one-sample Z-test?
What's with the Z in Z-test? In what way is it similar to a simple z or standard score?
For the following situations, write out a research hypothesis:a. Bob wants to know if the weight loss for his group on the chocolate-only diet is representative of weight loss in a large population
Flu cases this past flu season (4 months or 20 weeks) in the Butterfield, Kansas, school system were about 1 5 per week. For the entire state, the weekly average was 16 and the standard deviation
Mark's class just took the admission test for business school and averaged 83.4. contains the population of scores for the 10 other classes in Mark's university. How did Mark's class do?
Sales at Joe's BBQ in Salina, Kansas, were $$35,676$ for the first week of June 2015. How did Joe do compared with the rest of the barbecue restaurants in the county association?
Interview someone who uses statistics in his or her everyday work. It might be your adviser, an instructor, a researcher who lives on your block, a market analyst for a company, a city planner, or
We hope that you are part of a study group or, if that is not possible, that you have a telephone, e-mail, instant messaging, or webcam study buddy (or even more than one). And, of course, plenty of
Search through your local newspaper (or any other publication) and find the results of a survey or interview about any topic.Summarize the results and do the best job you can describing how the
Go to the library (either in person or online) and find a copy of a journal article in your own discipline. Then, go through the article and highlight the section (usually the "Results" section)where
Find five websites that contain data on any topic and write a brief description of what type of information is offered and how it is organized. For example, if you go to the mother of all data sites,
And the big extra-credit assignment is to find someone who actually uses Excel for daily data analysis needs. Ask why he or she uses Excel rather than a more specialized program such as SPSS or
Finally, as your last in this first set of exercises, come up with five of the most interesting questions you can about your own area of study or interest. Do your best to come up with questions for
The efficiency of the rank correlation test is 0.91. What does that value tell us about the test?
True or false: If there is no linear correlation between systolic and diastolic blood pressure, then those two variables are not related in any way.
True or false: If the sample data lead us to the conclusion that there is sufficient evidence to support the claim of a linear correlation between systolic and diastolic blood pressure, then we could
If each systolic reading is exactly twice the diastolic reading, what is the value of the linear correlation coefficient r?
If you had computed the value of the linear correlation coefficient to be 3.335, what should you conclude?
If the sample data were to result in the scatterplot shown here, what is the value of the linear correlation coefficient r?
The table below lists days of the week selected by a random sample of 1005 subjects who were asked to identify the day of the week that is best for quality family time (based on results from a
Without performing actual calculations, examine the frequencies in the table given with Exercise 1. Do you expect the value of the X2 test statistic to be large or small? Do you expect the P-value to
Goodness-of-Fit Test For the goodness-of-fit test described in Exercise 1, identify the number of degrees of freedom and the critical value of X2, assuming a 0.05 significance level.Exercise 1The
Is the hypothesis test left-tailed, right-tailed, or two-tailed?The table lists frequencies for randomly selected nonfatal occupation injuries arranged according to day of the week. Assume that we
Given that the P-value for the hypothesis test is 0.971, what do you conclude?The table lists frequencies for randomly selected nonfatal occupation injuries arranged according to day of the week.
Is the hypothesis test left-tailed, right-tailed, or two-tailed?Randomly selected subjects were asked about the use of marijuana for medical purposes. Assume that we want to use a 0.05 significance
Find the number of degrees of freedom and the critical value.Randomly selected subjects were asked about the use of marijuana for medical purposes. Assume that we want to use a 0.05 significance
Given that the P-value for the hypothesis test is 0.836, what do you conclude?Randomly selected subjects were asked about the use of marijuana for medical purposes. Assume that we want to use a 0.05
The following histogram is obtained from the daily rainfall amounts (in.) in Boston for a year. If we want to conduct a hypothesis test of a claim about the mean, there is a requirement that the
For the methods of this section, which of the following statements are true?a. The requirement of a simple random sample is satisfied if we have matched pairs of voluntary response data.b. If we have
Identify the null and alternative hypotheses resulting from the claim that the proportion of women who agree with the given statement is equal to the proportion of men who agree.Randomly selected

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