Stats study guide

Measures of dispersion describe typical values in the data. true false

false

The length of the box in the box-and-whisker plot portrays the: mean median range interquartile range

inter quartile range

Class limits are the: number of categories of the frequency distribution. number of data values falling within each class. lower and upper boundaries of each class. width of each class. mid-point of each class.

lower and upper boundaries of each class

A survey asks the respondent to indicate the number of cats in the household. The variable in question is an example of which type? qualitative, discrete qualitative, continuous quantitative, discrete quantitative, continuous

quantitative, discrete

The difference between the mean of a data set and the individual values of that set is known as the:

residual

The measure of central tendency that is least affected by extreme values is the: the weighted mean. the mean. the variance. the standard deviation. the median.

the median

Standardized values have no units, even though the original data, the standard deviation, and the mean may each represent units such as dollars, hours, or pounds. True False

true

A sample of 13 monthly sales figures (in thousands of dollars) are: 10, 6, 5, 10, 9, 7, 10, 9, 6, 8, 9, 6, and 6. The mean absolute deviation (MAD) of these numbers is?. Show three decimal places. 1.633 2.345 8.243 Can't be found

1.633

The Empirical Rule states that the percentage of observations in a data set (providing that the data set has a bell-shaped and symmetric distribution) that fall within one standard deviation of their mean is approximately:

68%

Which of the following techniques are applicable to quantitative data? The data array Frequency distributions Stem-and-leaf display Scatter diagram and Dotplot All of these

All

The difference between a histogram and a bar chart is that: A) the histogram reflects qualitative data while the bar chart represents quantitative data. B) the adjacent rectangles in a histogram have a gap while those for a bar chart do not. C) the histogram reflects quantitative data while the bar chart represents qualitative data. D) the adjacent rectangles in a bar chart have a gap while those for a histogram usually do not. E) Both answers C and D are correct.

C and D

ATP singles rankings for tennis players rank Rafael Nadal as 2 and Roger Federer as 1. This is an example of an interval scale. True False

False

The midrange is the average of the two middle data values. True False

False

The sole purpose of the U.S. Census Bureau is to simply count how many people live in the United States. True False

False

The statistic that describes the midpoint of the data which has just as many values above it as below it is known as the sample: mean median mode range standard deviation

Median

An automobile insurance agent believes that company A is more reliable than company B. Which scale of measurement does this information represent? Nominal Ordinal Interval Ratio

Ordinal

The difference between the highest and lowest values in the sample is known as the sample: mean median range proportion

Range

Which of the following is most likely a continuous quantitative variable? The number of gallons of paint purchased. The number of quarts of milk purchased. The population of Egypt. The temperature in a room. The number of times you sharpen your pencil working statistics problems.

The temperature in a room

Compared to the frequency distribution, the stem-and-leaf display provides more detail since it can describe the individual data values as well as show how many are in each group, or stem. True False

True

Stating that Wal-Mart's sales increased 6.2% this quarter when compared to last quarter is an example of descriptive statistics. True False

True

The box-and-whisker plot is a graphical device that simultaneously displays measures of central tendency and dispersion. True False

True

The median is the 5th decile. True False

True

The class interval is the: number of categories of the frequency distribution. number of data values falling within each class. lower and upper limits of each class. width of each class. mid-point of each class.

Width of each class

A requirement for a frequency distribution is that the set of classes must be mutually exclusive. This means that the set of classes must include all possible data values. a given data value can fall into only one class. the classes must have equal widths. classes must have an upper limit. classes must have a lower limit.

a given data value can fall into only one class

A summary measure that is computed using the entire population is called: a parameter a statistic a sample inferential statistics

a parameter

If the coefficient of correlation r is positive, the two variables x and y are directly linearly related inversely linearly related not linearly related not related

directly linearly related

In a positively skewed distribution, the: mean is greater than the median and the median is greater than the mode. mean is greater than the median and the median is smaller than the mode. mean is smaller than the median and the median is greater than the mode. mean is smaller than the median and the median is smaller than the mode. mean is equal to the median and the median is equal to the mode.

Mean is greater than the median and the median is greater than the mode

When data are collected in a statistical study for only a portion or subset of all elements of interest we are using a: sample parameter statistic population

Sample

Which of the following sample statistics is a measure of spread (dispersion)? Sample mean Sample standard deviation Sample median Sample proportion Sample mode

Sample standard deviation

Which of the following statements involve descriptive statistics as opposed to inferential statistics? The Alcohol, Tobacco and Firearms Department reported that Houston had 1,791 registered gun dealers in 1997. Based on a survey of 400 magazine readers, the magazine reports that 45% of its readers prefer double column articles. The FAA samples 500 traffic controllers in order to estimate the percent retiring due to job stress related illness. Based on a sample of 300 professional tennis players, a tennis magazine reported that 25% of the parents of all professional tennis players did not play tennis. The admission's office in a southern university samples 200 college students in business in order to estimate the percentage of business majors who prefer accounting to economics.

The Alcohol, Tobacco and Firearms Department reported that Houston had 1,791 registered gun dealers in 1997.

A sample of 13 monthly sales figures (in thousands of dollars) are: 10, 6, 5, 10, 9, 7, 10, 9, 6, 8, 9, 6, and 6. The standard deviation of these numbers is?. Show three decimal places. 3.349 1.830 1.633 Can't be found

1.830

Which of the following statements is false? Statistics can be divided into two branches: descriptive and inferential. The mean, median and mode, are measures of typicalness or central tendency. The range and standard deviation are measures of spread or dispersion or variability. A discrete quantitative variable can take on a value at any point along an interval. The four scales of measurement are important in determining appropriate methods for data description and analysis.

A discrete quantitative variable can take on a value at any point along an interval.

Which of the following statements involve inferential statistics as opposed to descriptive statistics? A total of 4,785 people voted for Mike Johnson in a local election. The FAA reported there were 200 near misses among airplanes last year. A class of fifty statistics students earned an average grade of 75.5. The city business office reported 40 building permits for new single-family housing units. Based on a sample of 500 subscribers, a local cable system estimates that forty percent of its subscribers watch a premium channel at least once per day.

Based on a sample of 500 subscribers, a local cable system estimates that forty percent of its subscribers watch a premium channel at least once per day.

The midway point between the upper and lower class limits for a frequency distribution is known as the: class interval. class width. class mark. class frequency. class average.

Class mark

In a raw data listing, data are listed in increasing or decreasing numerical order. True False

False

In inferential statistics, we simply summarize and describe the data we've collected. True False

False

In the nominal measurement scale, numbers represent "greater than" or "less than" measurements, such as rankings or preferences. True False

False

Quantitative variables usually represent membership in groups or categories. True False

False

Six classmates told you their scores on the last statistics exam. Based on this information, you conclude that the average exam score for the entire class was 82. This is an example of descriptive statistics. True False

False

The Empirical Rule states that approximately 68% of the observations in any distribution will fall within one standard deviation of the mean. True False

False

The appropriate methods for representing the data do not depend on whether the variable of interest is quantitative or qualitative. True False

False

The sample statistic is a characteristic of the sample that the population parameter attempts to estimate. True False

False

The set of classes in the frequency distribution should be selected so that any given value falls into at least one category. True False

False

A box plot shows the median but not the mean of a set of data. True False

True

Contingency tables are used primarily for counts involving qualitative data. True False

True

The scatterplot can simultaneously show values of two quantitative variables (y, or vertical axis, and x, or horizontal axis), such as height (x) and weight (y). True False

True

A summary measure that is computed from a sample to describe a characteristic of the population is called: a parameter a statistic a population inferential statistics

a statistic

The __________ is a graphical display providing cumulative values for frequencies, relative frequencies, or percentages. stem-and-leaf display dotplot line graph pie chart ogive

ogive

In a scatter diagram, data are represented as: dots which allow us to readily see the shape of the distribution as well as the high and low values. frequencies according to the relative length of a set of rectangles. a subset of the original digits as class descriptors. a circular display divided into sections based on the number of observations within the segments. pairs of known values of two variables, one being referred to as independent and the other, dependent.

pairs of known values of two variables, one being referred to as independent and the other, dependent.

The relative frequency distribution describes the number of observations that fall within each class. proportion of observations that fall within each class. number of observations that are within or below each of the classes. proportion of observations that are within or below each of the classes. None of these is correct.

proportion of observations that fall within each class

The measure of central tendency that is most affected by extreme values is the: range. mean. median. mode. coefficient of variation.

the mean