BS chap 1
A consumer reporting agency, in its rating of cars, indicates repair history with circles. The circles are either white, black, or half and half. To which level of data does this correspond? Discuss.
This corresponds to ORDINAL data because the SYMBOLS CAN BE RANKED
An agency has started charging a user fee to park at selected trailheads and cross-country ski lots. Some users object to this fee, claiming they already pay taxes for these areas. The agency has decided to randomly question selected users at fee areas in a region to assess the level of concern. a. Define the population of interest. b. Assume a sample of 250 is required. Suppose the agency questions the first 50 users encountered at each of 5 fee areas. Which sampling technique did the agency use?
a. People who park at the selected trailheads and cross-country ski lots. b. Convenience sampling
Describe how statistics could be used by a business to determine if the dishwasher parts it produces last longer than a competitor's brand.
statistical inference
A loan manager for Bank of the Cascades has the responsibility for approving automobile loans. To assist her in this matter, she compiled data on the following variables: car type, whether the car has ABS brakes, the company that produces the car, number of cylinders in the engine, horsepower rating of the engine, torque rating of the engine, 0 to 60 mph time in seconds, EPA rated mileage in city, EPA rated mileage on highway, curb weight in pounds, price of car as tested, and engine displacement in liters. Indicate the level of data measurement for each of the variables.
1. What is the level of data measurement for car type? > Nominal 2. What is the level of data measurement for whether the car has ABS brakes? > Nominal 3. What is the level of data measurement for the company that produces the car? > Nominal 4. What is the level of data measurement for the number of cylinders in the engine? > Ratio 5. What is the level of data measurement for the horsepower rating of the engine? > Ratio 6. What is the level of data measurement for the torque rating of the engine? >Ratio 7. What is the level of data measurement for the 0 to 60 mph time in seconds? > Ratio 8. What is the level of data measurement for the EPA rated mileage in city? >Ratio 9. What is the level of data measurement for the EPA rated mileage on highway? > Ratio 10. What is the level of data measurement for the curb weight in pounds? > Ratio 11. What is the level of data measurement for the price of car as tested?> Ratio 12. What is the level of data measurement for engine displacement in liters? > Ratio
Explain why a census does not necessarily have to involve a population of people. Use an example to illustrate.
A census examines an entire population. Recording the make of each vehicle owned by a company is a census.
Define what is meant by a leading question.
A leading question is worded in a way that will influence the response of the question.
Describe the difference between a statistic and a parameter.
A parameter is a descriptive numerical measure computed from an entire population. A statistic is the corresponding measure for a sample.
Briefly explain what is meant by an experiment and an experimental design
An experiment is any event for which the result is not known beforehand. Experimental design is a method for implementing an experiment and determining all of the information that should be recorded before, during and after the experiment is conducted
In your position as general manager for a fitness center, you have been asked to survey the customers of your location to determine whether they want to convert the racquetball courts to an aerobic exercise space. The plan calls for a written survey to be handed out to customers when they arrive at the fitness center. Your task is to develop a short questionnaire with at least three "issue" questions and at least three demographic questions. You also need to provide the finished layout design for the questionnaire.
Do you play racquetball? (Yes) (No) Would you use an aerobic exercise space? (Yes) (No) How many times per week do you visit the fitness center? (1) (2) (3) (4) (5) (More) What is your gender? (Male) (Female) What is your age group? (under 21) (21-35) (36-50) (over 50) To which political party do you belong? (Republican) (Democrat) (Other)
What is the difference between qualitative and quantitative data?
Qualitative data are measurements whose scale is inherently categorical. Quantitative data are measurements whose values are inherently numerical.
According to a report issued by an agency, it is estimated that southern fire ants spread at a rate of 4 to 5 miles a year. What data collection method do you think was used to collect this data? Explain your answer.
The data were collected by either direct observation or by experiment. Either the agency watched the spread of existing ants in the region, or it conducted an experiment to determine the spread of these ants under certain conditions.
Consider the graph on the right that appeared in a company annual report. What type of graph is this? Explain.
The graph is a bar chart because there are numerical values along only one axis
Review the accompanying figures and discuss any differences between the histogram (Figure 1) and the bar chart (Figure 2).
The histogram describes numerical information while the bar chart describes categories. Also, the bars in the histogram are adjacent while the bars in the bar chart are separated.
Suppose a large magazine would like to determine the average age and income of its subscribers. How could statistics be of use in determining these values?
The magazine could use statistical inference, particularly estimation, to determine these values by looking at a subset of the data.
If the manager at First City Bank surveys a sample of 100 customers to determine how many miles they live from the bank, is the mean travel distance for this sample considered a parameter or a statistic? Explain.
The mean travel distance is considered a statistic. Values computed from a sample are always considered statistics. In order for a value, such as an average, to be considered a parameter it must be computed from all items in the population.
Why is convenience sampling considered to be a nonstatistical sampling method?
The probability that an item is selected depends on the ease of selection.
As part of a consulting project for a local television station, a survey was conducted with 744 respondents. Of those responding, 32% indicated that they prefer to watch local news on this station. How might this survey have been conducted, and what type of bias could occur if that data collection method was used?
The survey may have been conducted by telephone interview. Some potential types of bias that could occur are interviewer bias, nonresponse bias, and selection bias.
During a recent political campaign, a news organization poll of eligible voters showed that one candidate would beat the other in the general election 47% to 44.5%. Are these values statistics or parameters? Explain.
The values are STATISTICS because they are based on A SIMPLE OF ELIGIBLE VOTERS
According to the U.S. Bureau of Labor Statistics, the annual percentage increase in U.S. college tuition and fees in 1995 was 6.0%, in 1999 it was 4.0%, and in 2004 it was 9.5%. Are these percentages statistics or parameters? Explain.
These percentages are parameters since they would include all U.S. colleges.
For the following situation indicate whether the statistical application is primarily descriptive or inferential. "The manager of Anna's Fabric Shop has collected data for 10 years on the number of each type of dress fabric that has been sold at the store. She is interested in making a presentation that will illustrate these data effectively."
This application is primarily descriptive in nature. The owner wishes to develop a presentation. She will most likely use charts, graphs, tables and numerical measures to describe her data.
Your manager has given you an Excel file that contains the names of the company's 500 employees and has asked you to sample 50 employees from the list. You decide to take your sample as follows. First, you assign a random number to each employee using Excel's random number function Rand(). Because the random number is volatile (it recalculates itself whenever you modify the file), you freeze the random numbers using the Copy—Paste Special—Values feature. You then sort by the random numbers in ascending order. Finally, you take the first 50 sorted employees as your sample. Does this approach constitute a statistical or a nonstatistical sample?
This is a statistical sample. Every employee has a chance of being selected using this method. In fact, this is an example of a simple random sample because every possible sample of size 50 has an equal chance of being selected.
a. collecting data on the percentage of drivers who stop at a certain stop light b. collecting data on the price of regular unleaded gasoline at gas stations in the state c. collecting data on customer satisfaction with the service provided by an investment firm
a. The data should be collected with direct observation so that the data collected are accurate. b. The data should be collected by telephone or written surveys because they are the cheapest and easiest methods. c. The data should be collected by telephone or written surveys because they are the cheapest and easiest methods.
A company was considering producing a new snack chip. To see if there was enough interest, 1,000 randomly selected people tried the chips and were asked if they liked the chips or not, whether they would be likely to purchase them if they were available, and how often they would be likely to purchase them. Of the 1,000 people, 642 liked the chips, 271 stated they would purchase them once a month, and 137 stated they would purchase them once a week. The company inferred from these results that in a region with a population of 1,000,000 people, sales would be about 800,000 bags of chips per month.
a. What specifically was estimated? The expected monthly sales of the chips in the region b. What conclusion was reached using the estimation? Sales would be about 800,000 bags of chips per month. c. Describe how the data were extracted and how they were used to produce the estimation. > The data came from the number of bags people in the sample would buy and a proportion was used to produce the estimate. d. Keeping in mind the goal of the estimation, discuss whether you believe that the estimation was successful and why. > The estimation was probably successful because it was based on market research. e. Describe what inferences were drawn as a result of the estimation. The 1,000 people would purchase about 800 bags of chips per month, so 1,000,000 people would purchase about 800,000 bags.
Indicate which sampling method would most likely be used in each of the following situations. a. an interview conducted with firefighter chiefs of a sample of cities in California b. a poll of voters regarding a referendum calling for a national highway development program c. a survey of people entering an amusement park in Orlando
a. Which sampling method would most likely be used in an interview conducted with > cluster sampling b. Which sampling method would most likely be used in a poll of voters regarding a referendum calling for a national highway development program? > stratified random sampling c. Which sampling method would most likely be used in a survey of people entering an amusement park in Orlando? > convenience sampling
a. star rating (0 to 4 stars) of a new movie b. age of the award winner for Best actress c. response to whether or not a hockey player scored a goal in the all-star game d. the distance (in miles, kilometers etc) between city A and city B
a. ordinal b. ratio c. nominal d. ratio
Suppose a student is asked to survey students at his university to determine if they are satisfied with the food service choices on campus. What types of biases must the student guard against in collecting the data? Assume that the student conducts a written survey.
nonresponse bias selection bias leading or poorly worded questions
If a pet store wishes to determine the level of customer satisfaction with its services, would it be appropriate to conduct an experiment? Explain.
No, because a written or telephone survey would be a much easier and cheaper way to obtain the customer satisfaction data.
