Unit 2: Analyzing Univariate Data Text: Chapter 1 Exploring Data AP Stats Theme I: A / B

Basic graphical displays Quantitative variables Categorical variables ( Qualitative) Dot plots Stem plots The variables are numeric. They represent a measurable quantity. For example, when we speak of the population of a city, we are talking about the number of people in the city - a measurable attribute of the city. Therefore, population would be a quantitative variable. Bar graphs Pie charts The values of a categorical variable are labels for the categories such as “ female” & “ males

Bar graphs Easier to make and read. More flexible than pie charts Can also compare any set of quantities that are measured in the same units Helps an audience grasp data quickly Used to compare the sizes of different groups.

Pie charts Awkward to make by hand, but software will do the job for you Must include all the categories that make up a whole Use only when you want to emphasize each category’s relation to the whole Helps an audience grasp data quickly

Dot plots Used to compare frequency counts within categories or groups. Is made up of dots plotted on a graph Each dot can represent a single observation from a set of data, or a specified number of observations from a set of data. The dots are stacked in a column over a category, so that the height of the column represents the relative or absolute frequency of observations in the category.

Dotplot continuous The pattern of data in a dotplot can be described in terms of symmetry and skewness only if the categories are quantitative. If the categories are qualitative (as they often are), a dotplot cannot be described in those terms

Stem plots used to display quantitative data, generally from small data sets (50 or fewer observations) the entries on the left are called stems; and the entries on the right are called leaves

Link for additional information http://faculty.washington.edu/wijsman/GRAPHS3.pdf

Assignments TPS 1.1, 1.2, 1.4, 1.5, 1.6