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| a characteristic that varies from one person or thing to another |
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| a numerically valued variable |
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| a nonnumerically valued variable |
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| a quantitative variable whose possible values can be listed |
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| a quantitative variable whose possible values frorm some interval of numbers |
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| values of a qualitative variable |
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| values of a quantitative variable |
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| values of a discrete variable |
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| values of a continuous variable |
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| each individual piece of data |
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| the collection of all observations for a particular variable |
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| the number of times a particular distinct value occurs |
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| frequency distribution of qualitative data |
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Definition
| a listing of the distinct values and their frequencies |
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| constructing a frequency distribution of qualitative data procedure |
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Definition
1. list the distinct values of the observations in the data set in the first column of a table
2. for each observation, place a tally mark in the second column of the table in the row of the appropriate distinct value
3. count the tallies for each distinct value and record the totals in the third column of the table |
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Definition
ratio of the frequency to the total number of observations
relative frequency = frequency / number of observations
percentage expressed as a decimal |
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| relative frequency distribution of qualitative data |
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Definition
| a listing of the distinct values and their relative frequencies |
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Term
| constructing a relative-frequency distribution of qualitative data procedure |
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Definition
1. obtain a frequency distribution of the data
2. divide each frequency by the total number of observations |
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| a disk divided into wedge-shaped pieces proportional to the relative frequencies of the qualitative data |
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Term
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Definition
| displays the distinct values of the qualitative data on a horizontal axis and the relative frequencies (or frequencies or percents) of those values on a vertical axis. The relative frequency of each distinct value is represented by a vertical bar whose height is equal to the relative frequency of that value. The bars should be positioned so that they do not touch each other. |
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| classes (categories, bins) |
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Definition
| groups of observations of quantitative data |
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| classes in which each class represents a single possible value |
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| method of grouping quantitative data using single-value classes |
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| each class consists of a range of values |
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| method of grouping quantitative data using class limits |
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| the smallest value that could go in a class |
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| the largest value that could go in a class |
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| the difference between the lower limit of a class and the lower limit of the next-higher class |
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| the average of the two class limits of a class |
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| method of grouping quantitative data by using cutpoints |
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| the smallest value that could go in a class |
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| the smallest value that could go in the next-higher class (equivalent to the lower cutpoint of the next-higher class) |
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| the difference between the cutpoints of a class |
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| the average of the two cutpoints of a class |
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Term
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Definition
displays the classes of the quantitative data on a horizontal axis and the frequencies (relative frequencies, percents) of those classes on a vertical axis. The frequency (relative frequency, percent) of each class is represented by a vertical bar whose height is equal to the frequency (relative frequency, percent) of that class. THe bars should be positioned so that they touch each other.
For single-value grouping, we use the distinct values of the observations to label the bars, with each such value centered under its bar.
For limit grouping or cutpoint grouping, we use the lower calss limits (or, equivalently, lower class cutpoints) to label the bars. |
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Definition
| a histogram that uses frequencies on the vertical axis |
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| relative-frequency histogram (percent histogram) |
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Definition
| a histogram that uses relative frequencies or percents on the vertical axis |
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Definition
| type of graphical display for quantitative data, particularly useful for showing relative positions of the data in a data set or for comparing two or more data sets |
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| procedure for constructing a dotplot |
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Definition
1. draw a horizontal axis that displays the possible values of the quantitative data
2. record each observation by placing a dot over the appropriate value on the horizontal axis
3. label the horizontal axis with the name of the variable |
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Term
| stem-and-leaf diagram (stemplot) |
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Definition
| method of displaying data |
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| each observation within a stemplot, consisting of all but the rightmost digit |
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Definition
| rightmost digit in a stemplot |
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| constructing a stemplot procedure |
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Definition
1. think of each observation as a stem--consisting of all but the rightmost digit--and a leaf, the rightmost digit
2. write the stems from smallest to largest in a vertical column to the left of a vertical rule
3. write each leaf to the right of the vertical rule in the row that contains the appropriate stem
4. arrange the leaves in each row in ascending order |
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| distribution of a data set |
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Definition
| a table, graph, or formula that provides the values of the observations and how often they occur |
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Definition
| distribution with one peak |
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| distribution with two peaks |
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| distribution with three or more peaks |
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| a distribution shape that can be divided into two pieces that are mirror images of each other |
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| the values of a variable for the entire population |
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| the values of a variable for a sample of the population |
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| population distribution (distribution of the variable) |
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Definition
| distribution of the population data |
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| distribution of the sample data |
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| a graph that has been cut off at the vertical axis |
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| a symbol representing an object or concept by illustration |
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