Many standard statistical methods that you will study in Part II of this book ar

Question

Many standard statistical methods that you will study in Part II of this book are intended for use with distributions that are symmetric and have no outliers. These methods start the mean and standard deviation, x bar and s. For example, standard methods would typically be used for the IQ and GPA data here data308.dat. (a) Find x bar and s for the IQ data. (Round your answers to two decimal places.) x bar = s = (b) Find the median IQ score. It is, as we expect, close to the mean. (c) Find the mean and median for the GPA data. The two measures of center differ a bit. (Round your answers to two decimal places.) mean = median = What feature of the data (make a stemplot or histogram to see) explains the difference?

Explanation / Answer

Note: I will explain the procedure, since no data is available.

Use excel to solve.
mean: "=AVERAGE(A1:A20)"     For 20 observations. Use the formula to find the mean and adjust the cell numbers to match the number of observations and also the column of interest(gpa or iq).

std. dev.: "=STDEV.S(A1:A20)"    This provides the std. dev. with bessel's correction, normally used for calculating std. dev of samples and not populations. Adjust the cell reference to use the formula for the right number of observations

Feature of data: Skewness. The data is a little skewed, and there are some outliers. Outliers can cause the mean to be affected much more than the median.

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