COMM3710 - Fall 2011 - Section 001 - Lecture Notes - 09/01

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If we were only interested in the sample then we wouldn’t need statistics. We want to generalize and know the significance.

Is it weird enough?
Is it significant?

Normal distribution – don’t violate this when using statistics

The sample is your data. Population is the “real world”.

Mean – the sum divided by the number of occurrences

Median – the middle point
Mode – the most frequent occurrence

N = number in population
n = number in sample

Greek letters are used in the population whereas regular letters are used in the sample.

Quantify the dispersion this is the first step.

X(bar) = Sum Xs/N

The magical 3-step journey
1) Variation = SUM X^2 - (SUM X)^2/N
2) Variance = Average Dispersion = SS/N = S^2 = d^2
3) Standard Deviation use the square root

The quantification of dispersion is the question that you really want to ask.

Make your homework neat. Put a cover page on your homework.