Statistics Exam 1
What does it mean when a part of the population is under-represented?
A part of the population is under represented when it proportionally smaller in a sample than in its population
Define experimental unit
A person, object or some other well defined item upon which treatment is applied
Number of channel is a ___ value
Discrete
Determine whether the following statement is true or false. Explain. A simple random sample is always preferred because it obtains the same information as other sampling plans but requires a smaller sample size.
False, because other sampling techniques may provide more information for less cost than a simple random sample
A student wanted to compare two types of commuting options. One type is carpooling and the other is taking a commuter train. It is a common belief that carpooling saves more time. This belief is tested by having 10 students commute to school by each mode of transportation and record the time of arrival at school each morning.A coin flip was used to determine which type of transportation that a student would use first. Results indicated that there was no difference in the two types of transportation. What is the treatment?
Types of transportation
The human resource department at a certain company wants to conduct a survey regarding worker benefits. The department has an alphabetical list of all 3306 employees at the company and wants to conduct a systematic sample of size 30. What is k?
3306/30=110 k=110
What is a bar graph?
A bar graph is a horizontal or vertical representation of the frequency or relative frequency of the categories
What is a Pareto chart?
A bar graph whose bars are drawn in decreasing order
What is a lurking variable?
A lurking variable is an explanatory variable that was not considered in a study, but that affects the value of the response variable in the study. In addition, lurking variables are typically related to explanatory variables in the study.
Define factor
A variable whose effect on the response variable is to be assessed by the experimenter
Define treatment
Any combination of values of the explanatory values
A poll is being conducted at a mall to obtain a sample of the population of an entire country. Who would be excluded from the survey and how might this affect the results of the survey?
Any person who does not shop at the mall is excluded
What are some solutions to nonresponse?
Attempt callbacks, offer rewards and incentives
A(n) _________ is obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups.
Cluster sample
Explain what is meant by confounding
Confounding in a study occurs when the effects of two or more explanatory variables are not separated. Therefore, any relation that may exist between an explanatory variable and the response variable may be due to some other variable or variables not accounted for in the study.
Size of a TV is a _____ variable
Continuous
A poll is being conducted at a mall to obtain a sample of the population of an entire country. What is the frame for this type of sampling?
Entire population of the country
For a poll of voters regarding a referendum calling for a national value dash added taxvalue-added tax, design a sampling method to obtain the inviduals in the sample. Be sure to support your choice.
For a poll of voters regarding a referendum calling for a national value dash added taxvalue-added tax, design a sampling method to obtain the inviduals in the sample. Be sure to support your choice.
Determine the level of measurement of the variable: Years of elections 1988,1992,1996,2000,2004
Interval
A student wanted to compare two types of commuting options. One type is carpooling and the other is taking a commuter train. It is a common belief that carpooling saves more time. This belief is tested by having 10 students commute to school by each mode of transportation and record the time of arrival at school each morning.A coin flip was used to determine which type of transportation that a student would use first. Results indicated that there was no difference in the two types of transportation. What type of experiment is this?
Matched pair
Screen type is a ____ variable
Qualitative
Determine whether the given value is a statistic or a parameter. A sample of seniors is selected and it is found that 45% own a vehicle.
Statistic because the value is a numerical measurement describing a characteristic of a sample.
Define statistics.
Statistics is the science of collecting, organizing, summarizing, and analyzing information to draw a conclusion and answer questions. In addition, statistics is about providing a measure of confidence in any conclusions.
To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Toyota selects every 1818th car that comes off the assembly line starting with the fifth until she obtains a sample of 40 cars. What kind of sampling was used?
Systematic
Researchers wanted to determine if there was an association between daily coffee consumption and the occurrence of skin cancer. The researchers looked at 93,093 women and asked them to report their coffee-drinking habits. The researchers also determined which of the women had nonmelanoma skin cancer. After their analysis, the researchers concluded that consumption of six or more cups of caffeinated coffee per day was associated with a reduction in nonmelanoma skin cancer. What is the explanatory variable?
The explanatory variable is consumption of caffeinated coffee.
Define response variable
The quantitative or qualitative variable for which the experimenter wishes to determine how its value is effected by the explanatory variable
In their report, the researchers stated that "After adjusting for various demographic and lifestyle variables, daily consumption of six or more cups was associated with a 30% reduced prevalence of nonmelanoma skin cancer." Why was it important to adjust for these variables?
The researchers may be concerned with confounding that occurs when the effects of two or more explanatory variables are not separated or when there are some explanatory variables that were not considered in a study, but that affect the value of the response variable.
Researchers wanted to determine if there was an association between daily coffee consumption and the occurrence of skin cancer. The researchers looked at 93,093 women and asked them to report their coffee-drinking habits. The researchers also determined which of the women had nonmelanoma skin cancer. After their analysis, the researchers concluded that consumption of six or more cups of caffeinated coffee per day was associated with a reduction in nonmelanoma skin cancer. What is the response variable in this study?
The response variable is whether the woman has nonmelanoma skin cancer or not.
When plotting an ogive, the plotted points have x-coordinates that are equal to the upper limits of each class.
True
A student wanted to compare two types of commuting options. One type is carpooling and the other is taking a commuter train. It is a common belief that carpooling saves more time. This belief is tested by having 10 students commute to school by each mode of transportation and record the time of arrival at school each morning.A coin flip was used to determine which type of transportation that a student would use first. Results indicated that there was no difference in the two types of transportation. What are the experimental units?
The students
A student wanted to compare two types of commuting options. One type is carpooling and the other is taking a commuter train. It is a common belief that carpooling saves more time. This belief is tested by having 10 students commute to school by each mode of transportation and record the time of arrival at school each morning.A coin flip was used to determine which type of transportation that a student would use first. Results indicated that there was no difference in the two types of transportation. What is the response variable?
The time of arrival
Determine whether the underlined value is a parameter or a statistic: One of the greatest baseball hitters of all time has a career batting average of 0.366
The value is a parameter because the careen at-bats of a baseball player are a population
Determine whether the quantitative variable is discrete or continuous. Volume of water in a swimming pool
The variable is continuous because it is not countable
Determine whether the variable is qualitative or quantitative: Price of a new computer
The variable is quantitative because it is a numerical measure.
Researchers wanted to determine if there was an association between daily coffee consumption and the occurrence of skin cancer. The researchers looked at 93,093 women and asked them to report their coffee-drinking habits. The researchers also determined which of the women had nonmelanoma skin cancer. After their analysis, the researchers concluded that consumption of six or more cups of caffeinated coffee per day was associated with a reduction in nonmelanoma skin cancer. What type of observational study was this?
This was a cross-sectional study because all information about the individuals was collected at a specific point in time.
A student wanted to compare two types of commuting options. One type is carpooling and the other is taking a commuter train. It is a common belief that carpooling saves more time. This belief is tested by having 10 students commute to school by each mode of transportation and record the time of arrival at school each morning.A coin flip was used to determine which type of transportation that a student would use first. Results indicated that there was no difference in the two types of transportation. Why is a coin used?
To eliminate bias as to which transportation was used first
For a poll of voters regarding a referendum calling for a national value dash added value-added tax, design a sampling method to obtain the individuals in the sample. Be sure to support your choice.
Use stratified sampling. Since this is a national issue, different geographical locations are likely to have similar views