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Lesson 1 - 0
Summary to
Exploring Data
Chapter Objectives• Use a variety of graphical techniques to display a
distribution. These should include bar graphs, pie charts, stemplots, histograms, ogives, time plots, and Boxplots
• Interpret graphical displays in terms of the shape, center, and spread of the distribution, as well as gaps and outliers
• Use a variety of numerical techniques to describe a distribution. These should include mean, median, quartiles, five-number summary, interquartile range, standard deviation, range, and variance
• Interpret numerical measures in the context of the situation in which they occur
• Learn to identify outliers in a data set
Section Objectives
• Identify the individuals and variables in a set of data
• Classify variables as categorical or quantitative
• Identify units of measurement for a quantitative variable
Vocabulary
• Individuals – objects described by a set of data; maybe people, animals or things
• Variable – any characteristic of an individual; can take on different values for different individuals
• Categorical variable – places an individual into one of several groups or categories
• Quantitative variable – takes numerical values; for which it makes sense to find an average!
• Distribution – tells us what values the variable takes on and how often it takes these values
• Inference – using a sample of data to infer (to draw conclusions) about a larger group of data
Activity• Hiring Discrimination – It just won’t fly! on pg 5
Captains Trial 1 Trial 2 Trial 3 Trial 4 Trial 5
Male
Female
Activity – Computer Assisted
Capt 0 1 2 3 4 5 6 7 8
M-Pct 0.000 0.001 0.020 0.106 0.265 0.333 0.208 0.059 0.006
Cum 0.000 0.001 0.021 0.127 0.392 0.725 0.933 0.992 ~1
Using Excel to help calculate the probabilities of having that number of male captains selected with the parameters given in the activity:
Cumulative probabilities don’t always add to 1 from a table due to round-off error. Almost 13% chance of this or more extreme result.
Later in the course we will cover this type of problem again in the non-AP portion of discrete random variables.
Categorical Variables
• From Mr. Starnes data collection sheet:– Gender M/F– Hair color Br/Bl/Rd/Gr– Restaurant– Birth date– Dominant hand R/L– Bathroom Y/N– Numbers (1-4) 1/2/3/4– S or Q S/Q– Heads or Tails H/T
Quantitative Variables
• From Mr. Starnes data collection sheet:– Hours of sleep 0-10– Number of siblings 0-8– Height 4’9” – 6’5”– SAT scores 400-800– Ounces of soda 0-64– Pulse 40-80– Days 0-10– Time spent 0-4– Instructor’s age 50-70
Summary and Homework
• Summary– A data set contains information on a number of
individuals– Information is often values for one or more
variables– Variables can be categorical or quantitative– Distribution of a variable describes what values it
can take on and how often
• Homework– Pg 7-8, problems 1, 3, 5, 7, 8