12.1 Sampling, Frequency Distributions, and Graphs

stem-and-leaf plot

A data presentation that separates each data item into two parts called a ______________.

random

A sample obtained in such a way that every member of the population has an equal chance of being selected is called a ____________ sample.

histogram

Data can be displayed using a bar graph with bars that touch each other. This visual presentation of the data is called a ______________. The heights of the bars represent the frequencies of the data values.

frequency distribution

If data values are listed in one column and the adjacent column indicates the number of times each value occurs, the data presentation is called a _______________.

grouped frequency distribution

If the data presentation in Exercise 2 is varied by organizing the data into classes, the data presentation is called a ______________. If one class in such a distribution is 80-89, the lower class limit is 80 and the upper class limit is 89.

frequency polygon

If the midpoints of the tops of the bars of a histogram are connected with straight lines, the resulting line graph is a data presentation called a _____________. To complete such a graph at both ends, the lines are drawn down to touch the horizontal axis.

true

True or False: A call-in poll on radio or television is not reliable because the sample is not chosen randomly from a larger population.

true

True or False: A deception in the visual display of data can result by stretching or compressing the scale on a graph's vertical axis.

false

True or False: A sample is the set of all people or objects whose properties are to be described and analyzed by the data collector.

false

True or False: One disadvantage of a stem-and-leaf plot is that it does not display the data items.