CH 2 Exploring Data With Tables and Graphs Flashcards
What term shows how data are partitioned among several categories (or classes) by listing the categories along with number (frequency) of data values in each of them?
Frequency distribution (Frequency table)
In regards to constructing frequency distributions, what term describes the smallest numbers that can belong to each of the different classes?
Lower class limits
In regards to constructing frequency distributions, what are the largest numbers that can belong to to each of the different classes?
Upper class limits
In regards to constructing frequency distributions, what are the numbers used to separate the classes, but without the gaps created by class limits?
Class boundaries
In regards to constructing frequency distributions, what term describes the values in the middle of the classes?
Class midpoints
In regards to constructing frequency distributions, what term describes the difference between two consecutive lower class limits in a frequency distribution?
Class width
What term describes when each class frequency is replaced by a percentage?
relative frequency distribution
How do you calculate the relative frequency for a class?
(frequency for a class) / (Sum of all frequencies)
What variation of frequency distribution is used when the frequency of each class is the sum of the frequencies for that class and all previous classes?
cumulative frequency distribution
What are some characteristics of approximately normal frequency distribution?
Frequencies start low, then increase to one or two high frequencies, and then decrease to a low frequency
The distribution is approximately symmetric
What does the presence of gaps in a frequency distribution suggest?
data are from two or more different populations
What term describes a graph consisting of bars of equal width drawn adjacent to each other where the horizontal scale represents classes of quantitative data values and the vertical scale represents frequencies?
histogram
List the important uses of a histogram:
Visually displays the shape of the distribution of the data
Shows the location of the center of the data
Shows the spread of the data
Identifies outliers
What has the same shape and horizontal scale as a histogram but the vertical scale uses relative frequencies?
Relative frequency histogram
What are four common histogram distribution shapes?
Bell shaped
Uniform distribution
Skewed to the right
Skewed to the left
What is the criteria for assessing normality with a Normal Quantile Plot?
Normal distribution: pattern is in reasonably close to a straight line and the points do not show some systematic pattern
What type of graph consists of quantitative data in which each data value is plotted as a point above a horizontal scale of values?
dotplot
What type of graph represents quantitative data by separating each value into two parts: the stem and the leaf?
stempot
What type of graph is made of quantitative data that has been collected at different points in time?
Time-series graph
What type of graph uses bars of equal width to show frequencies of categories of categorical data?
Bar graphs
What is a bar graph with the added stipulation that the bars are arranged in descending order?
Pareto Chart
What is a common graph that depicts categorical data as slices of a circle, in which the size of each slice is proportional to the frequency count for the category?
Pie Charts
What uses line segments connected to points located directly above class midpoint values?
Frequency Polygon
What is a variation of the frequency polygon that uses relative frequencies?
relative frequency polygon
What are the advantages of the relative frequency polygon?
two or more can be combined on a single graph for easy comparison
List two ways graphs can be deceptive:
Nonzero vertical axis
Pictographs
What exists when the values of one variable are somehow associated with the values of the other variable?
correlation
What exists between two variables when there is a correlation and the plotted points of paired data result in a pattern that can be approximated by a straight line?
linear correlation
What is a plot of paired (x,y) quantitative data with a horizontal x-axis and vertical y-axis?
scatterplot or scatter diagram
what is denoted by r, and measures the strength of the linear association between two variables?
linear correlation coefficient
What does the computed value of the linear correlation coefficient always fall between?
-1 and 1
Regarding linear correlation coefficient, an r value close to what number implies all the data fall exactly on a line?
1 or -1
What r value indicates that there is weak or no linear correlation?
if r is close to 0
When given a collection of paired sample data, what is the straight line that best fits the scatterplot of the data?
Regression line
