1. statistical method and data analysis - introduction
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Statistical Method and Data Analysis
INTRODUCTIONTO
STATISTICAL
METHODS&
DATAANALYSIS
What is Statistic?
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Why use Statistic?
Decision Makers Use Statistics To:
Present and describe business data andinformation properly
Draw conclusions about large groups ofindividuals or items, using information
collected from subsets of the individuals oritems.
Make reliable forecasts about a businessactivity
A branch of mathematics, taking andtransforming numbers into useful informationfor decision makers
Methods for processing & analyzing numbers
Methods for helping reduce the uncertaintyinherent in decision making
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Statistical Method
Descriptive statistics
Descriptive statistics comprises the statistical
methods dealing with the collection, tabulation
and summarization of data, so as to present
meaningful information
They are simply a way to describe our data
Collecting and describing data
Collect data
o e.g. Survey
Present data
o e.g. Tables and graphsCharacterize data
o e.g. Sample mean =
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Inferential statistics
Statistical inference, on the other hand,
consists of the methods involved with the
analysis and interpretation of data that will
enable the statistician to develop meaningful
inferences about the data
Drawing conclusions and/or making
o decisions concerning a population
based only on sample data
Estimationo
e.g.: Estimate the population meanweight using the sample meanweight
o Hypothesis testing
o e.g.: Test the claim that the
Statistical Method
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Drawing conclusions and/or makingdecisions
Type of Data
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Examples:
Marital Status
Political Party
Eye Color
(Defined categories)
Examples:
Number of Children
Defects per hour
(Counted items)
Examples:
Weight Voltage
(Measuredcharacteristics)
Population and Sample
Population
Sample
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Parametric & Non Parametric
Parametric
Non Parametric
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What is a Statistical
A statistical hypothesis is an assertion orconjecture concerning one or morepopulations.
The truth or falsity of the assertion isnever known with absolute certaintyunless we examine the entire
population.
Due to time and cost considerations,this option is rarely feasible.
Therefore we use SAMPLES and
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Tests of Hypotheses 9 Standard
1. Define the problem objective2. Formulate a null and alternative hypothesis3. Decide if the problem will be evaluated with a
one-tail or two-tail test4. Determine proper sample size to be taken.5. Determine the appropriate statistical test touse.6. Choose a critical value of a test statisticreflecting the
degree of uncertainty that can be tolerated(alpha risk).
7. Compute the calculated value of the teststatistic from
the sample information8. Compare the calculated value of the test
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Define the Problem Objective
KNOW what you want to prove (or disprove)BEFORE you do any data collection!
Start by completing the following sentence: Iam trying to prove that
Formulate the Null and Alternative
Hypotheses
The null (H0) and alternative (H1 or Ha)hypotheses are developed from theproblem statement.
The problem statement (what you are
trying to prove) becomes the alternativehypothesis.
The null hypothesis becomes what youare trying to disprove
Tests of Hypotheses
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One Tail Tests
If a test is established to determine whethera new population value is SMALLER orLARGER than the old population value, therisk of making an error in accepting Ha isplaced on only one end of the distribution:
Ho: NEW OLD Ho: NEW OLDHa:
NEW< OLD
Ha: NEW
> OLD
Tests of Hypotheses
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Two Tail Tests
If a test is established to determinewhether a new population value isDIFFERENT than the old population
value, the alpha risk is divided into twoparts:
Ho: NEW= OLD
Ha: NEW OLD
Tests of Hypotheses
Tests of Hypotheses
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