Mid-Term Today...

If you're in my statistics class, (Ag Ed ###,) here's what someone who went to the review session told me:

Most of the time, grouped data are considered to be ordinal. Percentages can be interval or ratio. Course grade is considered to be rank data, because it's not always the case that each grade is 10 points more than the other.

Skewness and normal is not synonymous, because you may have a bimodal polygon with 0 skewness, but its not normal.

Most measures of central tendency, variability, etc., cannot be determined from a frequency polygon, nor from grouped data, they must be determined from the raw data. But with a frequency polygon, you can see a tail better. With grouped data, you can't even tell your range, because you're not sure at what number the tail ends.

We don't need to know about z scores, nor the diff between kendall's tau b and c, nor chic squares, nor ogive curve.

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