MFC Statistics 2 - Dr Faraz Janan PDF

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Dr Faraz Janan...

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Statistics - II Central Limit Theorem(CLT):  If samples are taken from a population with any type distribution with mean and standard deviation, sample means will have a normal distribution Inferential Statistics:  Concerned with drawing conclusions about a population from a sample  Generally done through random sampling, followed by inferences made Estimation:  Estimating population values based on sample data (A section of the whole data set)

Z-score:  An observation's Z-score is a measure of how large or small that observation is relative to other observations in data set  Z tells us how many standard deviations x is above or below the mean o How different is your sample to the set

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X = observation S = sample standard deviation

68% of values within 1 standard deviation 95% of values within 2 standard deviations 99% of values within 3 standard deviations Normal Distribution:  Height of the curve represents relative frequency at which corresponding values occur  It is symmetric about the mean  P(x) decreases as x gets farther and farther away from the mean  It approaches the horizontal axis asymptotically: -infinity < x < +infinity When you check a z-score in the z-table, the number represents the amount of "things" that are below the z-score  Eg, z = 0.63, table shows 0.7357, then 73.57 people have a score below 63

Hypothesis Testing:  Use a statistical test to investigate whether a hypothesis about a population parameter is true or not A hypothesis is made about value of a population parameter, but the only facts avaliable to estimate true parameter are those provided by sample

If the statistic differs from the Hyp. Stated about parameter, a decision must be made as to whether or not this difference is significant. H0: Null Hyp. ; Contains hypothesised parameter value which will be compared with sample value Ha/H1: alternative Hyp. ; will be "accepted" only if H0 is rejected...