CH 1.3: Graphical Summaries

Question 1

Define Stem-and-Leaf Plots

Answer 1

Plots that consist of a stem, the leftmost one or two digits, and leaf which consists of the next digit in the data values. Used to show an informal summary about the data.

Question 2

Define Dotplot

Answer 2

It is a plot that show the concentrated frequency and gaps in data values. It is an informal summary of the data values.

Question 3

Define Histograms

Answer 3

Histogram can consist of a table of data or plot that shows the frequency, relative frequency and density of the data values over predetermined intervals.
+ Frequency: The number of data values in the set interval.
+ Relative Frequency: The number of data values in the set interval divided by the number of total values.
+ Density: Relative frequency divided by the set interval. (Used to proportion data)
+ Set Interval: When data is large log n or 2(n^1/3) can be used to set up a reasonable interval.
*Important to note that if the set intervals used in the histogram plot are not equal then the density value must be used to graph the plot’s y-axis.
**Also note that relative frequency can be obtained by multiplying the density and interval value in a histogram plot.

Question 4

When is a histogram plot symmetric?

Answer 4

If it right half is mirror image of its left half.

Question 5

When is a histogram skewed? Define the type of skewed.

Answer 5

When the plot is not symmetric.
+Right skewed/positively skewed is when the plot has long tail to the right, and the mean is greater than the median.
+Left skewed/negatively skewed is is when the plot has a not tail to the left and the mean is less than median.

Question 6

Define Unimodal

Answer 6

When a histogram plot has one peak/mode/local maximum.

Question 7

Define Bimodal

Answer 7

When a histogram plot has two peaks/modes/local maximums.

Question 8

Describe a boxplot

Answer 8

A graphic that presents the median, the first and third quartiles, and any outliers present.

Question 9

Define interquartile range

Answer 9

The difference between the third and first quartile. Also known as IQR.

Question 10

Define Outlier

Answer 10

Any data value in a box plot that is more or less than 1.5 of the IQR.

Question 11

Define Bivariate

Answer 11

Data where each item is a pair of values.

Question 11

Define Multivariate Data

Answer 11

Data for which each item consists of more than one value.