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business
business statistics in practice
Questions and Answers of
Business Statistics In Practice
a) For each sample size and sample standard deviation, calculate the estimated standard error.i) n = 100, s = 20 ii) n = 100, s = 5 iii) n = 400, s = 20 iv) n = 36, s = 5 v) n = 1,200, s = 20b)
a) In any distribution with finite mean and variance, how probable is it to find a score that falls 3 or more standard deviations from the mean? (Hint: A probability is expressed as a fraction from 0
At Pleasant Valley High, a very large school, math test scores are distributed normally with a mean of 50 points and a standard deviation of 20 points.a) What percentage of scores fall between 30
a) Use the chart in the Appendix B to find Z-scores that correspond to the following values for alpha:i) .05 for a one-tailed test ii) .01 for a one-tailed test iii) .05 for a two-tailed test iv) .01
From the population of all Woodlands University students, we draw a sample of 144 students to estimate the mean number of hours that students spend “on the internet” each week. (In other words,
Select a current issue for which opinions can be dichotomized (example: yes or no on whether bakers should be required to make cakes for same-sex weddings if they have religious objections to
Ask 20 of your friends a yes/no binary type of question and record their answers. This distribution will be considered the population, and its percentage of “yes” answers will be considered the
a) A battery manufacturer claims that battery life is 80 hours. Since we know that not all batteries will last exactly 80 hours, we understand that the claim really is that the mean life is 80 hours.
Educational Analytics Inc. claims to have developed a new math curriculum that will increase performance on tests of student comprehension of math concepts. The existing baseline for all kids tested
Here is a letter to a research team from a peer-reviewed journal to which the team has submitted a research report. Choose response a or b, and explain your answer.Dear Research Team:In view of the
Joe Candidate’s polling organization finds that in a random sample of 900 voters, 500 prefer Joe to his rival candidate in a two-person race. In your calculations, round answers to two decimal
We are trying to estimate how long it takes to prepare a school lunch. In a test kitchen, a sample of 100 school lunches was prepared. The average time per lunch was 10 minutes.Assume that we know
Return to the research question you asked at the end of Part One (in the section “Exercise for Part One”). Discuss how you would think about this question in terms of statistical inference.What
Read a research article in a peer-reviewed journal in a field of interest to you, and see how the authors set up their statistical inference. Do they use confidence intervals and/or hypothesis
Analyzing data from a large sample of countries (over 100), we find a .96 correlation of male life expectancy and female life expectancy.a) How would you interpret this? Is it surprising? Do you
This exercise is most easily completed with access to a computer and software; alternatively, you can use the formulas and do the computations with a calculator.Mario insists that tall men receive
This project is best carried out if you have access to a computer and statistical software because the calculations for the regressions are rather long.Collect men’s and women’s heights and
If you have access to the data sets on the companion website, you can carry out all the analysis yourself; if not, look at the output shown here and interpret the findings.First, review the income
Here are the music achievement scores for three groups of kids.Are these three groups performing at significantly different levels? Are the group means significantly different?a) Find the overall
We begin this exercise by showing some data analysis from the Small Student data set.Two variables in the Small Student data set are the number of hours per week students spend studying (studyhrs)
The 180 Students data set is also small, and it has information about real students at a large university. Students were asked questions about their activities such as study and employment hours. We
Look at the following table (Table 9.12) and discuss the findings. Table 9.12. T-test: Hours of sleep per night (SLEEPNUM) by gender category (GENDER), from the 180 Students data set data:sleepnum by
This exercise will take you through the steps in the calculation of a t-test for proportions.In the study of sexual behavior and attitudes in a large city (Laumann et al. 2004), the researchers
We are testing whether babies are born in equal proportions in all birth seasons (spring, summer, fall, winter). We have a sample of 200 children in which 50 were born in the spring, 50 in the
Suggest three research questions in areas of interest to you that would require a crosstab to explore the strength and statistical significance of a relationship between two variables. For each of
For this question, we will look at different ways of analyzing data about whether or not students get six hours of sleep a night. The tables have been produced from the data file called 180 Students.
Look at the following table and discuss what we have found.Return to the first table in the chapter (Table 10.1), the one about race and sleep, and compare it to the one shown above about class and
Examine Table 10.23, which presents another finding from Henderson’s Study Habits data set, and answer the following question.a) Is there a statistically significant difference in the way that men
Use the following table to answer the questions.a) Which variables (other than “constant”) were entered into this model as predictors of the violent crime rate in Chicago community areas?b) Which
a) Finish the short letter to former president Trump by filling in the blank:Dear Donald Trump: You have long argued that the presence of foreigners increases violent crime in the United States. But
Let’s venture a linear model with three predictor variables. Once again, the violent crime rate is the outcome variable, and our predictors are the percent of college grads, the percent of foreign
Select a good data analysis technique for the following variables, and explain your choice.Briefly describe how you would do the analysis and what you might propose as a research hypothesis.
Indicate the type of variable (numerical or categorical) and the level of measurement of the following data, using the terms nominal, ordinal, interval-ratio, and binary. Note: Identifying the level
Here are four sports problems, and three of them are based on true stories! Identify which problems call for a t-test, which call for a regression analysis, and which are handled by neither. So the
Answer the following without a calculator!a) Which of the following would be a plausible answer to this question: What was my car’s gas mileage on the trip from Chicago to Washington, DC?1,000
1) Place the following numbers on the number line:2) Which is greater? -5.5 +3 +1500 -10.12 -785 34 12 +1.8
What are the absolute values of the following numbers? c) -35.7 d) -3 a) 3 b) -5.5 c) -35.7 d) -3. 4 f) 0 g) 565 h) 1 i) 1/1 31 e) 3 4 j) -.50
OPERATIONS WITH FRACTIONS a) b) 415 + 715 23 54 59 e) c) d) 56 47 12 34 32 + 23 88 56 f) 57 ++ g) h) 83 +
Write each of these fractions in three different ways. 7837 a) .6 f) -12 92 b) g) c) 32% d) 33.3% e) 100% h) 3 i) .064 9
Square each of the following: a) 3 b) 39 c) 5.4 d) -5.4 e) f) .5 2 g) .75 h) 1 i)0 j) -1 k).32 1) - m) n) +25 2
1) Use a calculator to find the positive square root of the following numbers:a) 35b) 2c) 151d) .099e) .01f) 289 g) .3 h) .9 2) When we find the square root of a number between 0 and 1, which is
1) Ask 20 friends or classmates for their height and weight. For each person, mark the ordered pair (h, w) on a graph. What does the resulting graph or scatterplot look like?2) Ask 20 friends how
A company has a CEO, a CFO (chief financial officer), and a small number of other top executives who receive large compensation packages (i.e., salaries, stock options, and the like) as well as a
Find the mean, median and mode of the marbles distribution.Ethel has 15 marbles, Elmer has 8 marbles, Nancy has 10 marbles, Gladys has 12 marbles, Cyrus has 10 marbles, Augustus had 20 marbles, and
Make up an example that shows why the choice of measures of central tendency requires attention.
Calculate the range, variance, and standard deviations. Treat the data as sample data and use n – 1 in the division step for the variance and standard deviation.a) 2, 5, 8, 10, 12b) –1, 0, –3,
a) Can the standard deviation ever be 0?b) Can it ever be a negative number?c) What is the effect of a small number of extreme values or “outliers” on the standard deviation?d) The standard
Two school districts are looking at the results of a statewide reading test. Although the two districts have very similar means on the tests, the standard deviation of student test scores is much
The parent of one of the students finds out that her son’s score was 2 standard deviations below the mean of the Happy Valley test scores.a) In a sentence, give her a “ballpark” feeling of how
During the early months of the pandemic, many stock prices were very volatile (volatility is defined as a high standard deviation in a stock price during a specified time period). Which of the
Note that this question has been adapted from Freedman, Pisani, and Purves (2007). Three instructors are comparing scores on their finals. Each class had 99 students.For all three classes the range
Find the mean, the deviations from the mean, and the SD for the following batch of numbers.If you are using https://www.calculator.net/standard-deviation-calculator.html (or a similar site or the SD
For the following data and for each beach,• Create a frequency table of its recorded wave heights.• Find the mean, median, and mode.• Find the variance and standard deviation (use n – 1 in
Italians use the expression “a la Romana” to mean that a total restaurant bill is divided equally among all the diners in a group, regardless of how much each individual ordered. At what level of
A university department has the following distribution of salaries in dollars. (The list also shows the years at the university for each person.)a) What is the mean salary? Median salary? Modal
• Nominal variable: Record everyone’s eye color and create a frequency table, a pie chart, and a one-variable bar chart to display the information.• Numerical variable: Each person provides
Pick any one of the data sets posted on the companion website. Look at the codebook to understand the variables that were included in the data set. Using either SPSS/PASW or R-Commander, open the
Convert each fraction into a decimal fraction (divide bottom into top) and into a percentage (after the division, move the decimal point two places to the right).These conversions should be memorized
Percentage the following distributions to the nearest percentage point. a) In one week at Bill’s Bar and Grill, customers drank 340 Buds, 213 Bud Lights, 170 Labatt Blues, and 110 Goose Island
Do the following problems without a calculator:Explain why your answers make sense; if necessary, resort to thinking about a pie cut into wedges. a) 3 times 1 2 b) 3 divided by (Remember: To divide
Compute the following quantities:a) 1 times –3b) –4 divided by 2c) –6 times –7d) –6 divided by –7e) –7 plus 6f) –4 plus –5 g) –4 minus –5
a) Which is larger? Answer without a calculator:b) If a number is expressed as a fraction, and we increase the top (numerator), what happens to the number? Does it get bigger or smaller?c) If we
Think about your own high school to help you get started on thinking about schools and students. Suggest three variables that pertain to high school students as individuals(example: height). Try to
Now think about variables that pertain to high schools as places or organizations and suggest three variables (example: % of students who are female). Notice here how a binary variable at the
Thinking about high schools as places, suggest a possible relationship between two variables(a hypothesis), and identify the independent (IV or predictor) variable and dependent (DV or outcome)
For each variable, suggest a valid and reliable measurement procedure. Specify how the value for each case would be ascertained. Given your suggested operationalization of the variable, at what level
Identify some conceptual variables that present interesting challenges to operationalization and discuss them.Pair off, and, in each pair, develop a hypothesis that links your two variables in a
For each variable, suggest ways of collecting data so that the data are at the nominal, ordinal, interval-ratio (numerical), and dichotomous/binary levels of measurement. Note any situations that
For the following list, identify the best choice for an independent and a dependent variable, taking into account the type of case for which data were collected. Explain your choice. Remember that,
Come up with your own examples of pairs of variables (and the cases for which they are defined) that pose interesting problems in identifying the best choice of the IV and the DV.
As a class, do this exercise on formulating hypotheses with an independent and dependent variable:Each person writes on a slip of paper the name of a variable that could be used to characterize
Democratic, authoritarian, autocratic, totalitarian, liberal… we hear words like this all the time in the news to describe governments and states. But how would you define these terms in a way that
Imagine that you are trying to answer a research question about the relationship (if any) between a country’s petroleum resources and its political system. How would you define these variables in
Think of a team sport you like to watch or play, and suggest variables that might help to predict a team’s performance in the coming season.How would you define performance operationally (e.g., the
In recent years, some teams’ names and mascots have come to be considered offensive. Do you think this is a binary variable? Explain your answer, with examples.
Alex collected data from all students at Prairie University about their majors, and in each case, coded the college in which the major is located (e.g., Science and Health, Liberal Arts and Social
Aisha is studying the housing situation of Prairie State students. She asked each student for the square feet or square meters of their dwelling unit.a) What would be the best kind of graph to
Natasha looks at the data for the size of the dwelling units and says, “We really need to also find out how many people live in the dwelling unit.” She is asking Aisha to think about square
Create a frequency table, with percentages (rounded to one decimal place), for the following information.Can you make a bar chart for this information on graph paper or on a computer using either
A data mining routine has been applied to a transaction dataset and has classified 88 records as fraudulent (30 correctly so) and 952 as nonfraudulent ( 920 correctly so). Construct the
Table 5.5 shows a small set of predictive model validation results for a classification model, with both actual values and propensities.a. Calculate error rates, sensitivity and specificity using
The file BostonHousing.xls contains information on over 500 census tracts in Boston, where for each tract multiple variables are recorded. The last column (CAT.MEDV) was derived from MEDV, such that
The file Accidents.xls contains information on 42,183 actual automobile accidents in 2001 in the United States that involved one of three levels of injury: NO INJURY, INJURY, or FATALITY. For each
Return to the flight delays problem above and run it again, only this time choose a boosted classification tree. Leave the default number of weak learners, and select re-sampling. Set maximum levels
Consider again the data on used cars (ToyotaCorolla.xls) with 1436 records and details on 38 attributes, including Price, Age, KM, HP, and other specifications. The goal is to predict the price of a
A team at Hewlett-Packard collected data on a large number of email messages from their postmaster and personal email for the purpose of finding a classifier that can separate email messages that are
Universal Bank has begun a program to encourage its existing customers to borrow via a consumer loan program. The bank has promoted the loan to 5000 customers, of whom 480 accepted the offer. The
Using the eBay auction data (file eBayAuctions.xls) with variable Competitive as the target, partition the data into training \((50 \%)\), validation \((30 \%)\) and test sets \((20 \%)\).a. Run a
This problem uses the data set in HairCare-Product.xlsx, courtesy of SAS. In this hypothetical case, a promotion for a hair care product was sent to some members of a buyers club. Purchases were then
The Institute for Statistics Education at Statistics.com asks students to rate a variety of aspects of a course as soon as the student completes it. The Institute is contemplating instituting a
The dataset Cereals. \(x l\) s includes nutritional information, store display, and consumer ratings for 77 breakfast cereals.Data Preprocessing. Remove all cereals with missing values.a. Apply
Impact of September 11 on Air Travel in the United States. The Research and Innovative Technology Administration's Bureau of Transportation Statistics conducted a study to evaluate the impact of the
The time plot in Figure 17.18 describes actual quarterly sales for a department store over a 6-year period (data are available in Department Store Sales.xls, data courtesy of Chris Albright).a. The
Figure 17.21 shows a time plot of monthly sales for a souvenir shop at a beach resort town in Queensland, Australia, between 1995-2001 (data are available in SouvenirSales.xls, source: Hyndman, R.J.
The output in Figure 18.9 from applying Holt-Winters exponential smoothing to data, using "optimal" smoothing constants.a. The value of zero that is obtained for the trend smoothing constant means
The time plot in Figure 18.10 describes actual quarterly sales for a department store over a 6 -year period (data are available in DepartmentStoreSales.xls, data courtesy of Chris Albright).a. Which
Social media ha, given a boost to the artisan and craft trades. Many people embrace pastimes such as beer brewing, bread making, and pottery making. Social media provides both • mechanism for •
Consider the following text version of a post to an online learning forum in a statistics course:a. Identify 10 non-word tokens in the passage.b. Suppose that this passage constitutes a document to
In this problem you will use the data and scenario described in this chapter's example, in which the task is to develop a model to classify documents as either auto-related or electronics-related.a.
Farming is an extremely demanding job whose success depends largely on the dedication of the farmers. In order to tackle the rigorous tasks of the trade, farmers must be in good physical and mental
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