STATS 1.1 1.2 1.3 2.1 2.3 2.4 2.5
True or False? A statistic is a measure that describes a population characteristic.
False. A statistic is a measure that describes a sample characteristic.
T/F Data at the ordinal level are quantitative only.
False. Data at the ordinal level can be qualitative or quantitative.
T/F In a frequency distribution, the class width is the distance between the lower and upper limits of a class.
False. In a frequency distribution, the class width is the distance between the lower or upper limits of consecutive classes.
Why is a sample used more often than a population?
It is usually impossible to count the entire population. It is usually impossible to count every single member of a population. Counting every single member of the population is called a census.
Determine if the survey question is biased. If the question is biased, suggest a better wording. How often do you eat fruit during an average month? Is the question biased?
No, because it does not lead the respondent to any particular answer.
Name each level of measurement for which data can be qualitative.
Nominal and Ordinal
The jersey numbers for players on a football team are listed below. 18 20 55 19 10 5 16 6 32 13 21 8 11 23 1 14 2 25 3 45 38 30 15 29 17 66 28 Identify the level of measurement of the data set. Explain your reasoning.
Nominal. The data are categorized using numbers, but no mathematical computations can be made.
Name each level of measurement for which data can be quantitative.
Ordinal, Interval, and Ratio
What are some benefits of representing data sets using frequency distributions?
Organizing the data into a frequency distribution can make patterns within the data more evident.
Determine whether the data set is a population or a sample. Explain your reasoning. The height of each student in a classroom.
Population, because it is a collection of heights for all students in the classroom.
Determine whether the data set is a population or a sample. Explain your reasoning. The salary of each baseball player in a league.
Population, because it is a collection of salaries for all baseball players in the league.
Describe the relationship between quartiles and percentiles.
Quartiles are special cases of percentiles. Upper Q 1Q1 is the 25thpercentile, Upper Q 2Q2 is the 50th percentile, and Upper Q 3Q3 is the 75th percentile.
What is the difference between relative frequency and cumulative frequency?
Relative frequency of a class is the percentage of the data that falls in that class, while cumulative frequency of a class is the sum of the frequencies of that class and all previous classes.
What is replication in an experiment? Why is replication important?
Replication is repetition of an experiment under the same or similar conditions. Replication is important because it enhances the validity of the results.
Determine whether the data set is a population or a sample. Explain your reasoning. A survey of one quarter of an audience for a game show.
Sample, because the collection of surveys for one quarter of the audience is a subset of all the people in the audience.
What are the two main branches of statistics?
The two main branches of statistics are descriptive statistics and inferential statistics.
Why is the standard deviation used more frequently than the variance?
The units of variance are squared. Its units are meaningless.
What is the definition of median?
The value that lies in the middle of the data when the data set is ordered.
Determine whether the variable is qualitative or quantitative. Explain your reasoning. favorite song
The variable is qualitative because a favorite song describes an attribute
Determine whether the variable is qualitative or quantitative. Explain your reasoning. Medal won in race
The variable is qualitative because medal won in race describes an attribute or characteristic.
Determine whether the variable is qualitative or quantitative. Explain your reasoning. places of birth:
The variable is qualitative because places are attributes or labels.
Determine whether the variable is qualitative or quantitative. Explain your reasoning. responses on an opinion poll
The variable is qualitative because responses are attributes or labels.
Determine whether the variable is qualitative or quantitative. Explain your reasoning. telephone numbers:
The variable is qualitative because telephone numbers are attributes or labels.
The following appear on a physician's intake form. Identify the level of measurement of the data. (a)Year of birth (b)Happiness level (scale of 0 to 10) (c)Allergies (d)height
a: interval b: ordinal c: nominal d: ratio
The graph to the right shows the annual number of fatalities, in thousands, for certain years. Identify the level of measurement of the data listed on the horizontal and vertical axes in the figure. Identify the level of measurement of the data listed on the horizontal axis in the figure. Choose the correct answer below. Identify the level of measurement of the data listed on the vertical axis in the figure. Choose the correct answer below.
horizontal: interval vertical: ratio
The graph to the right shows the number of cities with certain average annual rainfall amounts (in inches). Identify the level of measurement of the data listed on the horizontal and vertical axes in the graph. Identify the level of measurement of the data listed on the horizontal axis in the graph. Choose the correct answer below. Identify the level of measurement of the data listed on the vertical axis in the graph. Choose the correct answer below.
horizontal: ratio vertical: ratio
left and right skewed
left(negative) mean , median , mode right(positive) mode, median, mean
types of measurement scales
nominal, ordinal, interval, ratio The level of measurement of data determines which statistical calculations are meaningful. The four levels of measurement, in order from lowest to highest, are nominal, ordinal, interval and ratio. The table below summarizes what calculations are meaningful for each level.
The list of books that your friend read for school for the past five months is shown below. Kiss The Dead Private London Gone Girl Spring Fever The Forgotten Identify the level of measurement of the data set. Explain your reasoning.
nominal. the data are categorized using names, labels, or qualities, but the data cannot be ranked or arranged in order.
Determine whether the underlined value is a parameter or a statistic. The average score for a class of 28 students taking a calculus midterm exam was 72%. Is the value a parameter or a statistic?
parameter. bc the value is a numerical measurement describing a characteristic of the population.
Use the Venn diagram to identify the population and the sample. Choose the correct description of the population. Choose the correct description of the sample.
population: The income of home owners in the county. sample: The income of home owners in the county who have a garage.
What is the difference between a census and a sampling?
A census includes the entire population. A sampling includes only part of the population.
What is the difference between a frequency polygon and an ogive?
A frequency polygon displays class frequencies while an ogive displays cumulative frequencies.
What is the difference between a parameter and a statistic?
A parameter is a numerical description of a population characteristic. A statistic is a numerical description of a sample characteristic.
How is a sample related to a population?
A sample is a subset of a population.
True or False? A population is the collection of some outcomes, responses, measurements, or counts that are of interest.
False. A population is the collection of ALL outcomes, responses, measurements, or counts that are of interest.
Identify the sampling techniques used, and discuss potential sources of bias (if any). Explain. Assume the population of interest is the student body at a university. Questioning students as they leave a university dorm, a researcher asks 390 students about their drinking habits. What type of sampling is used? What potential sources of bias are present, if any? Select all that apply.
Convenience sampling is used, because students are chosen due to convenience of location. The sample only consists of members of the population that are easy to get. These members may not be representative of the population. Because of the personal nature of the question, students may not answer honestly.
Choose the data set where the median and mode of the set are equal. A. 3,3,10,10 B. 4,4,4,5,6,6,6 C. 4,8,12,16,16,20 D. 1,1,7,7,7,8,8
D. 1,1,7,7,7,8,8
Which data set has the least sample standard deviation?
Data set (i), because it has more entries that are close to the mean.
Which data set has the greatest sample standard deviation?
Data set (ii), because it has more entries that are farther away from the mean.
Which data set has the least sample standard deviation?
Data set (iii), because it has more entries that are close to the mean.
(a) Which data set has the greatest sample standard deviation?
Data set (iii), because it has more entries that are farther away from the mean.
Use the given minimum and maximum data entries, and the number of classes, to find the class width, the lower class limits, and the upper class limits. minimum=7, maximum=76, 7 classes
Each class has a lower class limit, which is the least the least number that can belong to the class, and an upper class limit, which is the greatest the greatest number that can belong to the class. The class width is the distance between lower (or upper) limits of consecutive classes. The difference between the maximum and minimum data entries is called the range. To find the class width, determine the range of the data, divide the range by the number of classes, and then round up to the next convenient number. If the range divided by the number of classes is a whole number, use the next whole number as the class width to ensure that there is enough space in the frequency distribution for all the data entries. To find the range, subtract the given minimum from the given maximum. 76−7=69 Part 5 Now determine the class width. Class width = RangeNumber of classes = 69/7 = 10 (Round up to the nearest whole number.) Part 6 Use the minimum data entry as the lower limit of the first class. To find the remaining lower limits, add the class width to the lower limit of the preceding class. Part 7 The first class's lower limit is the minimum 7. The next lower limit is 7+10=17. (Type a whole number.) Part 8 The next lower limit is 17+10=27. (Type a whole number.) Part 9 Repeat the previous steps to find the lower limit for all 7 classes. The lower limits for all 7 classes are 7 comma 17 comma 27 comma 37 comma 47 comma 57 comma 677, 17, 27, 37, 47, 57, 67. (Type a whole number. Use a comma to separate answers as needed.) Part 10 The upper limit of the first class is one less than the lower limit of the second class, 17. Part 11 The upper limit of the first class is 17−1=16. (Type a whole number.) Part 12 To find upper limits of the other classes, add the class width to the upper limit of the previous class. The next class's upper limit is 16+10=26. (Type a whole number.) Part 13 Repeat the previous steps to find the upper limit for all 7 classes. The upper limits for all 7 classes are 16 comma 26 comma 36 comma 46 comma 56 comma 66 comma 7616, 26, 36, 46, 56, 66, 76. (Type a whole number. Use a comma to separate answers as needed.) Part 14 Thus, the class width is 10. The lower class limits are 7, 17, 27, 37, 47, 57, and 67. The upper class limits are 16, 26, 36, 46, 56, 66, and 76.
T/F A placebo is an actual treatment.
False. A placebo is a fake treatment.
A pharmaceutical company wants to test the effectiveness of a new allergy drug. The company identifies 250 females 30-35 years old who suffer from severe allergies. The subjects are randomly assigned into two groups. One group is given the new allergy drug and the other is given a placebo that looks exactly like the new allergy drug. After six months, the subjects' symptoms are studied and compared. Answer parts (a) through (c) below. (a) Identify the experimental units and treatments used in this experiment. Choose the correct answer below. (b) Identify a potential problem with the experiment design being used and suggest a way to improve it. Choose the correct answer below. (c) How could this experiment be designed to be a double-blind? Choose the correct answer below.
(a) The experimental units are the 30- to 35-year-old females being given the treatment. The treatment is the new allergy drug. (b) There may be a bias on the part of the researcher if the researcher knows which patients were given the real drug. (c) The study would be a double-blind study if both the researcher and the patient did not know which patient received the real drug or the placebo.
1.how to find range: 2.What is an advantage of using the range as a measure of variation? 3.What is a disadvantage of using the range as a measure of variation?
1. The range is found by subtracting the minimum data entry from the maximum data entry. 2.It is easy to compute. 3.it uses only two entries from the data set.
1.What is a similarity between the Empirical Rule and Chebychev's Theorem? 2.What is a difference between the Empirical Rule and Chebychev's Theorem?
1.Both estimate proportions of the data contained within k standard deviations of the mean. 2.The Empirical Rule assumes the distribution is aproximately symmetric and bell-shaped and Chebychev's Theorem makes no assumptions.
What are some benefits of representing data sets using frequency distributions? What are some benefits of using graphs of frequency distributions? 1What are some benefits of representing data sets using frequency distributions? 2What are some benefits of using graphs of frequency distributions?
1Organizing the data into a frequency distribution can make patterns within the data more evident. 2It can be easier to identify patterns of a data set by looking at a graph of the frequency distribution.
Suppose a survey of 535 women in the United States found that more than 63% are the primary investor in their household. Which part of the survey represents the descriptive branch of statistics? Make an inference based on the results of the survey. Choose the best statement of the descriptive statistic in the problem. Choose the best inference from the given information.
63% of women in the sample are the primary investor in their household. There is an association between U.S. women and being the primary investor in their household.
A data set includes the entries 3,4,5,7,7,and 10. Complete the data set with an entry between 1 and 10 so that the median and mode of the set are equal.
7
What is an inherent zero? Describe three examples of data sets that have inherent zeros and three that do not. Select three examples of data sets that have inherent zeros below. Select three examples of data sets that do not have inherent zeros below.
An inherent zero is a zero that implies none. have: Average monthly precipitation in inches, Average age of college students in years, Maximum wind speed during a hurricane dont have: A student's level of happiness measured from 0 to 10, Temperature in degrees Fahrenheit, Average IQ score of a high school class
Two types of survey questions are open questions and closed questions. An open question allows for any kind of response; a closed question allows for only a fixed response. An open question and a closed question with its possible choices are given below. List the advantages and disadvantages of each question. Open question: What can be done to get students to eat healthier foods? Closed question: How would you get students to eat healthier foods? 1. Mandatory nutrition course 2. Offer only healthy foods in the cafeteria and remove unhealthy foods 3. Offer more healthy foods in the cafeteria and raise the prices on unhealthy foods What are the advantages of an open question? Select all that apply. What are the disadvantages of an open question? Select all that apply. What are the advantages of a closed question? Select all that apply. What are the disadvantages of a closed question? Select all that apply.
An open question allows the respondent to go in-depth with their answer. An open question allows for new solutions to be introduced. It is difficult to compare the results of surveys with open questions. It is difficult to quantify the responses of open questions. The form of the question may influence the opinion of the respondent. It is possible to automate the collection of results for closed questions. It is easy to quantify and compare the results of surveys with closed questions. Closed questions may not provide appropriate alternative responses. The form of the question may influence the opinion of the respondent.
What is the difference between class limits and class boundaries?
Class limits are the least and greatest numbers that can belong to the class. Class boundaries are the numbers that separate classes without forming gaps between them. For integer data, the corresponding class limits and class boundaries differ by 0.5.
What is the difference between class limits and class boundaries?dup
Class limits are the least and greatest numbers that can belong to the class. Class boundaries are the numbers that separate classes without forming gaps between them. For integer data, the corresponding class limits and class boundaries differ by 0.5. In a frequency distribution, each class has a lower class limit, which is the least number that can belong to the class, and an upper class limit, which is the greatest number that can belong to the class. Also, class boundaries are the numbers that separate classes without forming gaps between them. For data that are integers, subtract 0.5 from each lower limit to find the lower class boundaries. To find the upper class boundaries, add 0.5 to each upper limit.
Identify the sampling techniques used, and discuss potential sources of bias (if any). Explain. After a flood, a disaster area is divided into 150 equal grids. Twenty of the grids are selected, and every occupied household in the grid is interviewed to help focus relief efforts on what residents require the most. What type of sampling is used? What potential sources of bias are present, if any? Select all that apply.
Cluster sampling is used, since the disaster area is divided into grids, and some of those grids are selected and everyone in those grids is interviewed. Certain grids may have been much more severely damaged than others. Severely damaged grids may have fewer occupied households. Certain grids may have been much more severely damaged than others. The grids that are selected may not be representative in terms of damage.
Determine whether the statement is true or false. If it is false, rewrite it as a true statement. More types of calculations can be performed with data at the nominal level than with data at the interval level.
False. More types of calculations can be performed with data at the interval level than with data at the nominal level. Data at the nominal level can be put in a category. Data at the interval level can be put in a category, put in order, and you can find differences between values. Therefore, more types of calculations can be performed with data at the interval level than with data at the nominal level.
After constructing a relative frequency distribution summarizing IQ scores of college students, what should be the sum of the relative frequencies?
If percentages are used, the sum should be 100%. If proportions are used, the sum should be 1.
Why should the number of classes in a frequency distribution be between 5 and 20?
If the number of classes in a frequency distribution is not between 5 and 20, it may be difficult to detect any patterns.
Why should the number of classes in a frequency distribution be between 5 and 20? dup
If the number of classes in a frequency distribution is not between 5 and 20, it may be difficult to detect any patterns. A frequency distribution is a table that shows classes or intervals of data entries with a count of the number of entries in each class. When constructing a frequency distribution from a data set, the first step is to decide on the number of classes to include in the frequency distribution. The number of classes should be between 5 and 20; otherwise, it may be difficult to detect any patterns.
What is the difference between an observational study and an experiment?
In an experiment, a treatment is applied to part of a population and responses are observed. In an observational study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions.
What is the difference between an observational study and an experiment? experiment
In an experiment, a treatment is applied to part of a population and responses are observed. In an observational study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions. In an experiment, a treatment is applied to part of a population and responses are observed. The researcher in an experiment deliberately influences the responses. In an observational study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions. The researcher in an observational study does not influence the responses.
What are some benefits of using graphs of frequency distributions?
It can be easier to identify patterns of a data set by looking at a graph of the frequency distribution.
Identify the sampling techniques used, and discuss potential sources of bias (if any). Explain. In 1965, researchers used random digit dialing to call 1400 people and ask what obstacles kept them from buying insurance. What type of sampling was used? What potential sources of bias were present, if any? Select all that apply.
Simple random sampling was used, since each number had an equal chance of being dialed, so all samples of 1400 phone numbers had an equal chance of being selected. Individuals may have refused to participate in the sample. This may have made the sample less representative of the population. Telephone sampling only includes people who had telephones. People who owned telephones may have been older or wealthier on average, and may not have been representative of the entire population. Individuals may have not been available when the researchers were calling. Those individuals that were available may have not been representative of the population.
Identify the sampling techniques used, and discuss potential sources of bias (if any). Explain. Every tenth person entering a mall is asked to choose his or her favorite store from a list of five different stores that includes a description of each. What type of sampling is used? What potential sources of bias are present, if any? Select all that apply.
Systematic sampling is used, because every tenth person is selected. The wording of the question may direct respondents towards a particular store. If there is a regular pattern to the people entering the store, the sample may not be representative.
Use the given minimum and maximum data entries, and the number of classes, to find the class width, the lower class limits, and the upper class limits. minimum=8, maximum=83,6 classes
The class width is 13. Part 2 Choose the correct lower class limits below. D. 8, 21, 34, 47, 60, 73 Your answer is correct. Part 3 Choose the correct upper class limits below. C. 20, 33, 46, 59, 72, 85
Use the given minimum and maximum data entries, and the number of classes, to find the class width, the lower class limits, and the upper class limits. minimum=19, maximum=124, 8 classes
The class width is 1414. (Type a whole number.) Part 2 Choose the correct lower class limits below. C. 19, 33, 47, 61, 75, 89, 103, 117 Part 3 Choose the correct upper class limits below. D. 32, 46, 60, 74, 88, 102, 116, 130
Use the given minimum and maximum data entries, and the number of classes, to find the class width, the lower class limits, and the upper class limits. minimum=10, maximum=72, 7 classes
The class width is 9. (Type a whole number.) find class width by max-min divide by 7 classes round to whole number for example 7.4 would be 8. Part 2 Use the minimum as the first lower class limit, and then find the remaining lower class limits. The lower class limits are 10 comma 19 comma 28 comma 37 comma 46 comma 55 comma 6410, 19, 28, 37, 46, 55, 64. (Type a whole number. Use a comma to separate answers as needed.) Part 3 The upper class limits are 18 comma 27 comma 36 comma 45 comma 54 comma 63 comma 7218, 27, 36, 45, 54, 63, 72. (Type a whole number. Use a comma to separate answers as needed.)
True or False? It is impossible for the Census Bureau to obtain all the census data about the population of the United States.
The correct answer is the statement is True because it is impossible to gather information about the entire population of any country because the population is always changing.
What is the definition of mode?
The data entry that occurs with the greatest frequency.
the four levels of measurement
The four levels of measurement, in order from lowest to highest, are nominal, ordinal, interval, and ratio. Data at the nominal level of measurement are qualitative only. Data at this level are categorized using names, labels, or qualities. No mathematical computations can be made at this level. Data at the ordinal level of measurement are qualitative or quantitative. Data at this level can be arranged in order, or ranked, but differences between data entries are not meaningful. Data at the interval level of measurement are quantitative only. Data at this level can be ordered and differences between data entries are meaningful, but a zero entry is not an inherent zero. Data at the ratio level of measurement are quantitative only. Data at this level are similar to data at the interval level, with the added property that a zero entry is an inherent zero.
A study of 802 senior citizens shows that participants who exercise regularly exhibit less of a decline in the cognitive ability than those who barely exercise at all. From this study, a researcher infers that your cognitive ability increases the more you exercise. What is wrong with this type of reasoning?
The inference may incorrectly imply that exercise increases a person's cognitive ability. The study shows a slower decline in cognitive ability.
Explain how the interquartile range of a data set can be used to identify outliers.
The interquartile range (IQR) of a data set can be used to identify outliers because data values that are greater than Upper Q 3 + 1.5 (IQR)Q3+1.5(IQR) or less than Upper Q 1 - 1.5 (IQR)Q1−1.5(IQR) are considered outliers.
Determine whether the underlined number describes a population parameter or a sample statistic. Explain your reasoning. Sixty−seven of the 98 passengers aboard an airship survived an explosion.
The number is a population parameter because it is a numerical description of all of the passengers that survived.
Determine whether the underlined number describes a population parameter or a sample statistic. Explain your reasoning. A survey of 2214 adults in a country found that 80% think that militant terrorists are a major threat to the well-being of their country.
The number is a sample statistic because it describes the people in a sample, which is a subset of all of the people in the country.
Determine if the survey question is biased. If the question is biased, suggest a better wording. Why is eating ice cream bad for you?
The question is biased. The wording "How do you think eating ice cream affects your health?" would be better.
Determine whether the approximate shape of the distribution in the histogram shown is symmetric, uniform, skewed left, skewed right, or none of these. Justify your answer. dup
The shape of the distribution is approximately uniform because the bars are approximately the same height.
Determine whether the approximate shape of the distribution in the histogram shown is symmetric, uniform, skewed left, skewed right, or none of these. Justify your answer.
The shape of the distribution is symmetric, but not uniform, because a vertical line can be drawn down the middle, creating two halves that look approximately the same.
Explain the relationship between variance and standard deviation. Can either of these measures be negative? Explain.
The standard deviation is the positive square root of the variance. The standard deviation and variance can never be negative. Squared deviations can never be negative.
Determine whether the following statement is true or false. If it is false, rewrite it as a true statement. A placebo is an actual treatment.
The statement is false. A placebo is a fake treatment. A placebo is a fake treatment used in experiments. To minimize the possibility of the subjects reacting favorably to a placebo, the subjects will typically be blinded as to whether they are receiving a real treatment or the placebo.
Determine whether the following statement is true or false. If it is false, rewrite it as a true statement. A sample statistic will not change from sample to sample.
The statement is false. A sample statistic can change from sample to sample. The statement is false. A sample statistic can change from sample to sample. A population parameter is constant for a population.
T/F For data at the interval level, you cannot calculate meaningful differences between data entries.
The statement is false. A true statement is "For data at the interval level, you CAN calculate meaningful differences between data entries."
Determine whether the following statement is true or false. If it is false, rewrite it as a true statement. Data at the ratio level cannot be put in order.
The statement is false. A true statement is "Data at the ratio level can be placed in a meaningful order."
The goals scored per game by a soccer team represent the first quartile for all teams in a league. What can you conclude about the team's goals scored per game?
The team scored fewer goals per game than 75% of the teams in the league. About one quarter of the data will fall below the first quartile, and about three quarters will fall above the first quartile. Therefore, the team scored fewer goals per game than 75% of the teams in the league.
How are the data sets the same? How do they differ?
The three data sets have the same mean but have different standard deviations.
Determine whether the statement is true or false. If it is false, rewrite it as a true statement. Some quantitative data sets do not have medians.
The statement is false. All quantitative data set have medians.
T/F Some quantitative data sets do not have medians.
The statement is false. All quantitative data set have medians.
T/F An ogive is a graph that displays relative frequencies.
The statement is false. An ogive is a graph that displays cumulative frequencies.
Determine whether the statement is true or false. If it is false, rewrite it as a true statement. It is impossible to have a z-score of 0.
The statement is false. A z-score of 0 is a standardized value that is equal to the mean. Having a z-score of 0 means that the value being tested is equal to the mean.
Determine whether the statement is true or false. If it is false, rewrite it as a true statement. The 50th percentile is equivalent to Q1.
The statement is false. The 50th percentile is equivalent to Q2. The 50th percentile is equivalent to the median, or Q2. In some rare occurrences, the 50th percentile is also equal to the mean.
Determine whether the following statement is true or false. If it is false, rewrite it as a true statement. The mean is the measure of central tendency most likely to be affected by an outlier.
The statement is true.
A student's IQ score is in the 91st percentile on an intelligence scale. Make an observation about the student's IQ score.
The student has a higher IQ score than 91% of the students in the same age group. The percentiles of a data set divide the data set into 100 equal parts. If a value is the 91st percentile of a data set, then 91 of the 100 parts are below this value, or 91%.
A student's score on an actuarial exam is in the 78th percentile. What can you conclude about the student's exam score?
The student scored higher than 78% of the students who took the actuarial exam. Since the student is in the 78th percentile, that means that 78% of the students who took the actuarial exam fall below that score. Therefore, the student scored higher than 78% of the total number of students.
Determine whether the study is an observational study or an experiment. Explain. To study the effects of social media on teenagers' brains, researchers showed a few dozen teenagers photographs that had varying numbers of "likes" while scanning the reactions in their brains.
The study is an experiment, because it applies a treatment to the teenagers
Determine whether the study is an observational study or an experiment. Explain. In a survey of 1002 adults in a country, 54% said the country's leader should release all medical information that might affect their ability to serve.
The study is observational, because it does not apply a treatment to the adults.
(b) How are the data sets the same? How do they differ?
The three data sets have the same mean, median and mode but have different standard deviations.
A motorcycle's fuel efficiency represents the ninth decile of vehicles in its class. Make an observation about the motorcycle's fuel efficiency.
The motorcycle's fuel efficiency is greater than the fuel efficiency for 90% of vehicles in its class. The deciles of a data set divide the data set into 10 equal parts. If a value is the ninth decile of a data set, then 9 of the 10 parts are below this value, or 90%.
Determine whether the statement is true or false. If it is false rewrite it as a true statement An outlier is any number above Q3 or below Q1.
This statement is false. A true statement is "An outlier is any number above Q3+1.5(IQR) or below Q1−1.5(IQR) are considered outliers."
T/F When each data class has the same frequency, the distribution is symmetric.
True, when each data class has the same frequency the distribution is symmetric.
T/F A data set can have the same mean, median, and mode.
True. A data set can have the same mean, median, and mode.
Determine whether the statement is true or false. If it is false, rewrite it as a true statement. The second quartile is the median of an ordered data set.
True. About one half of the data fall on or below the second quartile. The same is true for the median.
T/F Class boundaries ensure that consecutive bars of a histogram touch.
True. Because consecutive bars of a histogram must touch, bars must begin and end at class boundaries instead of class limits.
T/F The mean is the measure of central tendency most likely to be affected by an outlier.
True. The mean is the measure of the central tendency and is most likely affected by an extreme value(outlier), because the mean considers each and every value for it's calculation. Moreover the mean gets mostly affected if there is a existence of outlier in the data compared to any other statistical method.
T/F The midpoint of a class is the sum of its lower and upper limits divided by two.
True. The midpoint of a class is the sum of its lower and upper limits divided by two.
Describe the difference between the calculation of population standard deviation and that of sample standard deviation. Question content area bottom Part 1 Let N be the number of data entries in a population and n be the number of data entries in a sample data set. Choose the correct answer below.
When calculating the population standard deviation, the sum of the squared deviation is divided by N, then the square root of the result is taken. When calculating the sample standard deviation, the sum of the squared deviations is divided by n−1, then the square root of the result is taken.
Given a data set, how do you know whether to calculate σ or s?
When given a data set, one would have to determine if it represented the population or if it was a sample taken from the population. If the data are a population, then σ is calculated. If the data are a sample, then s is calculated. Note that σ represents the population standard deviation and s represents the sample standard deviation. One would have to use the given information carefully to decide whether the data represents the population or it is a sample taken from the population.
What is the difference between a random sample and a simple random sample? random
With a random sample, each individual has the same chance of being selected. With a simple random sample, all samples of the same size have the same chance of being selected.
What is the difference between a random sample and a simple random sample?
With a random sample, each individual has the same chance of being selected. With a simple random sample, all samples of the same size have the same chance of being selected.
Identify the population and the sample. Describe the sample data set. A survey of 139 law firms in a country found that the average hourly billing rate for partners was $586. Identify the population. Choose the correct answer below. Identify the sample. Choose the correct answer below. Describe the sample data set. Choose the correct answer below.
population: all law firms in the country sample: the law firms that were surveyed described sample set: The average hourly billing rate for partners of 139 law firms was $586.
In a poll, 1,003 women in a country were asked whether they favor or oppose the use of "federal tax dollars to fund medical research using stem cells obtained from human embryos." Among the respondents, 48% said that they were in favor. Identify the population and the sample. What is the population in the given problem? Choose the correct answer below. Identify the sample for the given problem. Choose the correct answer below.
population: all women in the country sample: the 1,003 women selected
The regions of a country with the six highest levels of coal production last year are shown below. 1. Northern 2. Eastern 3. Southwest 4. Southeast 5. Western 6. Northwest Determine whether the data are qualitative or quantitative and identify the data set's level of measurement. Are the data qualitative or quantitative? What is the data set's level of measurement?
qualitative ordinal
The temperatures (in °F) of air samples taken simultaneously over a glacier are shown below. 22.3 25.2 21.3 24.7 22.1 26.8 23.3 21.8 23.6 Determine whether the data are qualitative or quantitative and identify the data set's level of measurement. Are the data qualitative or quantitative? What is the data set's level of measurement?
quantitative interval
types of measurement scales yes n no
yes n no
Both data sets have a mean of 235. One has a standard deviation of 16, and the other has a standard deviation of 24. Which data set has which deviation?
(a) has a standard deviation of 24 and (b) has a standard deviation of 16, because the data in (a) have more variability.
Suppose a survey of 977 business owners found that more than 23% bought flood insurance. Which part of the survey represents the descriptive branch of statistics? Make an inference based on the results of the survey. Choose the best statement of the descriptive statistic in the problem. Choose the best inference from the given information.
23% of business owners in the sample bought flood insurance. Most business owners do not buy flood insurance.
