Statisitics

· The weight of cats compared to the weight of dogs

· High temperature in a city from day to day

· Most common type of weather in certain cities

· Most frequent nut in a jar of mixed nuts

Ways to Represent Data:

Pictograph

1. What do the above frequency table and corresponding pictograph show us?

2. What type of data must a pictograph have, categorical or numerical?

Dot Plots (Line Plots)

1. What does the dot plot tell us?

2. What do you about the score of 52?

3. What do you notice between 88 and 97?

4. Does the dot plot use categorical or numerical data?

Important definitions:

Outlier:

Cluster:

Gap:

Histogram:

On the provided histogram label an outlier, a cluster, and a gap.

Note the “squiggly” line next to the zero. What does it mean?

Stem and Leaf Plots

1. What does this stem and leaf plot show us?

2. Does a stem and leaf plot need categorical or numerical data?

Back-to-Back Stem and Leaf Plots

3. What was the highest score in each class?

4. What was the lowest score in each class?

Histograms and Bar Graphs

Compare the histogram and bar graph above.

1. Does order of the rectangles matter?

2. Is data numerical or categorical?

3. Is an even scale used?

4. Why did we say that our converted dot plot (of the test scores) was a histogram and not

a bar graph?

5. Of the displays we've covered (pictograph, dot plot, stem-and-leaf plot) which does each

one relate best to, histogram or bar graph?

Circle Graphs (Pie Charts)

The information in the table is based on survival and death rates of the crew and passengers in various ticket classes on the Titanic.

Step 1: Find the percentages for each category. (Total is the 1491 deaths.)

(If you round, be sure that your final numbers add to 100%.)

Step 2: Find the number of degrees necessary for that percentage.

Example: If first class is 25%, then the number of degrees is 25% of 360o which is

(.25)(360) = 90o.

Step 3: Draw your circle and measure the degrees with a protractor (or estimate the best you

can)!

Book Questions p.567

1. a. Discuss when a pictograph might be more appropriate than a circle graph.

b. Discuss when a circle graph might be more appropriate than a bar graph.

c. Give an example of a set of data for which a stem and leaf plot would be more informative

than a histogram.

2. Explain whether a circle graph would change if the amount of data in each category were

doubled.

3. Explain why the sum of the percents in a circle graph should always be 100%. How could it

happen that the sum is only close to 100%?