Chapters 1-2
Slate is a daily magazine on the Web. Its business activities can be described by a number of variables. What is the level of measurement for each of the following variables? -The number of hits on their website on Saturday between 8:00 a.m. and 9:00 a.m. -The departments, such as food and drink, politics, foreign policy, sports, etc. -The number of weekly hits on the Sam's Club ad. -The number of years each employee has been employed with Slate.
- The number of hits on their web site on Saturday has a significant zero point and the ratio between two numbers meaningful. So they are ratio level of measurement. -The departments are different from each other but have no meaning other than identification. So they are nominal level of measurement. -The number of weekly hits on the Sam's Club ad has a significant zero point and the ratio between two numbers meaningful. So they are ratio level of measurement. -The number of years each employee has been employed has a significant zero point and the ratio between two numbers meaningful. So they are ratio level of measurement.
pie chart
A chart that shows the proportion or percentage that each class represents of the total number of frequencies.
bar chart (relative frequency bar chart)
A graph that shows qualitative classes on the horizontal axis and the class frequencies on the vertical axis. The class frequencies are proportional to the heights of the bars.
Relative Class Frequencies
Captures the relationship between a class total and the total number of observations
Explain the difference between a discrete and a continuous variable.
Discrete variables can assume only certain values, but continuous variables can assume any values within some range.
Exits along interstate highways were formerly numbered successively from the western or southern border of a state. However, the Department of Transportation has recently changed most of them to agree with the numbers on the mile markers along the highway. What level of measurement were data on the consecutive exit numbers? What level of measurement are data on the milepost numbers? The newer system provided information on the distance between exits.
One exit number is higher or lower than another, but the differences between them are not the same. So the exit number is ordinal level of measurement. The milepost number has a significant zero point and the ratio between two numbers meaningful. So they are ratio level of measurement. The newer system provided more information, namely the distance between exits.- True
For each of the following, determine whether the group is a sample or a population.
Participants in a study for a new cholesterol drug- SAMPLE Drivers who received speeding ticket in Kansas City last month- POPULATION People on welfare in Cook County (Chicago, IL) - POPULATION The 30 stocks that make up the Dow Jones Industrial average- SAMPLE
What is the level of measurement for each of the following variables?
Student IQ Ratings- Interval Distance students travel to class-Ratio Jersey #s of the soccer team-Nominal Student's DOB-Nominal Student's academic class..Fresh/Soph/Jr/Senior- Ordinal Number of hours students study per week- Ratio
Exits along interstate highways were formerly numbered successively from the western or southern border of a state. However, the Department of Transportation has recently changed most of them to agree with the numbers on the mile markers along the highway.
a) What level of measurement were data on the consecutive exit numbers?- Ordinal b) What level of measurement are data on the milepost numbers?- Ratio c)The newer system provided information on the distance between exits.- True
The manager of the BiLo Supermarket in Mt. Pleasant, Rhode Island, gathered the following information on the number of times a customer visits the store during a month. The responses of 51 customers were: a. Starting with 0 as the lower limit of the first class and using a class interval of 3, organize the data into a frequency distribution. b. Describe the distribution. Where do the data tend to cluster? c. Convert the distribution to a relative frequency distribution.
b. The largest group of shoppers (21) shop at the BiLo Supermarket 3, 4, or 5 times during a one-month period. Somecustomers visit the store only 1 time during the month, butothers shop as many as 15 times. c.Number of PercentVisits of Total 0 up to 3 17.653 up to 6 41.186 up to 9 25.499 up to 12 7.8412 up to 15 5.8815 up to 18 1.96 Total 100.00
Explain the difference between qualitative and quantitative variables.
qualitative- non numerical quantitative- numerical
class frequency
the number of observations in the data set falling into a particular class
A poll solicits a large number of college undergraduates for information on the following variables: the name of their cell phone provider (AT&T, Verizon, and so on), the numbers of minutes used last month (200, 400, for example), and their satisfaction with the service (Terrible, Adequate, Excellent, and so forth). What is the level of measurement for each of these three variables? -The Cell phone provider -The number of minutes used -Satisfaction with the service
-Nominal -Ratio -Ordinal The cell phone providers are different from each other but have no meaning other than identification. So they are nominal level of measurement. The minutes used has a significant zero point and the ratio between two numbers meaningful. So they are ratio level of measurement. Satisfaction ratings are higher or lower than one another, but the differences between them are not the same. So the satisfaction ratings are ordinal level of measurement.
frequency distribution
A grouping of quantitative data into mutually exclusive and collectively exhaustive classes showing the number of observations in each class.
As part of a research project, you need to report the average profit as a percentage of revenue for the #1-ranked corporation in the Fortune 500 for each of the last 10 years.
A population is employed because the information is easy to find and there are only 10 observations in the entire population.
Explain the difference between a sample and a population.
A population is the entire group which you are studying. A sample is a subset taken from a population.
You are looking forward to graduation and your first job as a salesperson for one of five large pharmaceutical corporations. Planning for your interviews, you will need to know about each company's mission, profitability, products, and markets.
A population is used because the information is easy and relatively quick to collect for only five companies.
Statistics 201 is a course taught at a university. Professor Rauch has taught nearly 1,500 students in the course over the past 5 years. You would like to know the average grade for the course based on all 1,500 students.
A population is used because the professor likely has grades readily available from every student over the past 5 years.
You are shopping for a new MP3 music player such as the Apple iPod. The manufacturers advertise the number of music tracks that can be stored in the memory. Usually, the advertisers assume relatively short, popular songs to estimate the number of tracks that can be stored. You, however, like Broadway musical tunes and they are much longer. You would like to estimate how many Broadway tunes will fit on your MP3 player.
A sample works because it is difficult to locate every musical and the length of every song.
frequency table
A table for organizing a set of data that shows the number of times each item or number appears.
