Stats

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TSTICS FOR INTRODUGTORY

COURSES

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STATISTICS - A set of tools for collecting, oreanizing, presenting, and analyzing numerical facts or observations. I . Descriptive Statistics - procedures used to organize and present data in a convenient, useable. and communicable form.

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MEAN -The ooint in a distribution of measurements about which the summeddeviationsare equal to zero. Average value of a sample or population. POPULATION MEAN SAMPLE MEAN

2. Inferential Statistics - procedures employed to arrive at broader generalizations or inferences from sample data to populations. -l STATISTIC - A number describing a sample characteristic. Results from the manipulation of sample data according to certain specified procedures. DATA - Characteristics or numbers that a r e c o l l e c t e db y o b s e r v a t i o n . J POPULATION - A complete set of actual or potential observations. J J - A number describing a PARAMETER population characteristic; typically, inferred f r o m s a m p l es t a t i s t i c .

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Note: The mean ls very sensltlveto extrememeasurementsthat are not balancedon both sides. I WEIGHTED MEAN - Sum of a setof observations multiplied by their respectiveweights, divided by the sum of the weights: 9, *, *, -LWEIGHTED MEAN ; w h e r ex r , : w e i g h t , ' x ,- o b s e r v a t i o nG : n u m b e ro f fr g o b s e r v a i i o n r d u p s . ' C a l c u l a t e do m a p o p u l a t i o n . sample.or gr6upings in a frequencydistribution. Ex. In the FrequencVDistribution below, the meun is 80.3: culculatbd by- using frequencies for the wis. When grouped, use clossmidpointsJbr xis. in observation a or J MEDIAN - Observation potenlial set that divides the set so that the same number of observationslie on each side of it. For an odd number of values.it is the middle value; for an even number it is the averageof the middle two. Ex. In the Frequency Distribution table below, the median is 79.5. f MODE - Observationthat occurs...