Hey how you going buddy
ECON 141 is basically economics and statistics combined in one.
The first two chapters we've covered so far as basically these;
* Going over basic statistical analysis, like mode, mean, median of number sets and data
* We also went over how to find area's under the normal curve. These are basic STAT 170/171 skills (as in, finding the area to the RIGHT of a curve after a certain point).
Also things like finding areas (probabilities, which can also be convereted into percentages) using the formulas;
z = y - |u
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The 'z' score you look up in the 'z' table is the 'y' value you want to find, minus the average, all divided by the standard deviation. For example if the answer is 1.06, you look up 1.06 in the Z table (look at 1.0... then find the 0.06 in the vertical column).
This will gives you a number, say 0.2734 for example, and thats the probability of area to the RIGHT of the curve.
Let's say your 'z' score was -1.06 - since the curve is symmetrical you just have to do "1 minus the score of the positive 1.06".
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Note this rule - this applies to HEAPS of formulas in statistics. It's the 'y' value minus the average, divided by a standard deviation.
This will also apply to 't' statistics (We use T statistics when we cant measure the whole population and we don't have the REAL standard deviation because it takes too much time to measure everything, so we just use a sample)
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Confidence intervals --> When we use hypothesis tests we want to be 95% confident of our results. This is discussed soon in the lecture notes I think......
It's usually --
AVERAGE NUMBER (PLUS OR MINUS) the 95% confidence number times the STANDARD ERROR
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Also remember that we just learned something new compared to our old stats - Variance.
The variance is standard deviation squared. So we square root V(X) to get sigma.
To find variance, its in the book. I think its something like the first number minus the average, all squared... then add it to the {next number minus the average... all squared} But dont quote me I forgot ;P
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Im not saying Im a pro @ this subject. I got 69 in stat 170 and I was expecting higher since I was on like 93% for in-class crap! But yeah good luck with it if u need hope gimme a pop on msn !!
sabdow@gmail.com
