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LSP 121 -- 9/9/10

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Course Topics

• Descriptive Statistics, the Normal Distribution, Correlation, Probability, Risk, Measurement Units, Relational Databases, Positional Number Systems, Algorithms, Intro to Computer Programming using Alice Animations.

Activity 1

• Complete Activity 1, which is to work in groups to submit background information on group members.

Descriptive Statistics

• A univariate dataset contains only one variable.

• Descriptive statistics allow us to get a sense of a dataset without looking at every observation in detail.

• Common descriptive statistics include the average, standard deviation, minimum (Q0), first quartile (Q1), median (Q2), third quartile (Q3) and maximum (Q4).

• Example: Hypothetical Test Scores (HTS)
  90  79  39  98  75  93  85  5  91  93

• The average the n observations x₁, ... , x_n is
  x = (x₁ + ... + x_n) / n

• The average of HTS is 77.8.

• Here are the sorted HTS observations:
  5  39  75  79  85  90  91  93  93  98

• The median is the middle observation in the sorted list.

• If n is even, take the median to be the average of the two middle observations.

• The second quartile is the same as the median.

• Median of HTS is 87.5.

• The first quartile (Q1) is the median of the bottom half of the list.

• If n is odd, include the middle observation in the bottom half of the list.

• Q1 of HTS is 75.

• The third quartile is the median of the top half of the list.

• If n is odd, include the middle observation in the top half of the list.

• Q3 of HTS is 93.

• The interquartile range (IQR) is defined to be Q3 - Q1.

• The interquartile range of HTS is IQR = 93 - 75 = 18.

• Use SPSS to compute the univariate statistics for the HTS Dataset:
  Mean   Q0 (minimum)   Q1 (1st quartile)   Q2 (median)   Q3 (3rd quartile)   Q4 (maximum)

  Note: there is more than one algorithm (actually about 8) for computing Q1 and Q3; SPSS might produce slightly different values for Q1 and Q3 than the ones obtained by hand calculations. The Tukey's Hinges method for computing Q1 and Q3 is the method we are using for our hand calculations.

Boxplots

• See the document Boxplots.

• Create the boxplot for the Bank Waiting Data using SPSS.

• You will not be asked to create boxplots for any activities, homework assignments, or exams. You will be asked to interpret boxplots.

Histograms

• See the document Histograms.

• Create the histogram for the Bank Waiting Data using SPSS.

• You may be asked to draw a histogram for the midterm exam.

Collect Data for Homework 1

• Collect the time for each person in the class to count off 30 seconds.

• See Homework 1 for details.

• Example for HW1: using SPSS, find the following descriptive statistics for the National Bureau of Standards prototype 10g weight weighings in nbs-10.xls:
  Q0   Q1   Q2   Q3   Q4   x   SD+

  Also find the z-scores.

Activity 2

• Here is the Activity 2 Description.

• To complete Activity 2:
  1. Download the Excel file univariate.xls and importing both worksheets into SPSS.

  2. Compute the histogram, average, standard deviation, minimum, maximum, median, first quartile and third quartile of these datasets:
     Age of U.S. Presidents at Inauguration
     Illinois Precipitation in January.