chap 1 statistik
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BEKA2453
STATISTICS & NUMERICAL
METHOD
Chapter 1
Introduction to StatisticsMiss Arfah Ahmad
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Learning OutcomeAt the end of the chapter you should be able to:
Study the basic introductory concept of
statistics including the branches of statistics,
the basic terms of statistics and types of
variables.
Use graphical and numerical methods to
describe a data set.
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What is Statistics The science of collecting, organizing,
summarizing and analyzing information in
order to draw conclusions.
Types of statistics:
1. Descriptive statistics
2. Inferential statistics
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What is Statistics DescriptiveStatistics
organizing and summarizing the informationcollected. Descriptive statistics describes the
information collected through numericalmeasurements, charts, graphs
Inferential Statistics
uses the methods that generalize resultsobtained from a sample to the population andmeasure their reliability.
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Basic terms Population consists of all items
Sample certain elements in the population(subset of population)
Random Sample
sample drawn in such away that each element of the population hasthe chance of being selected.
Element/number
a specific subject or
individual about which the information iscollected.
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Basic terms Variable characteristic of the individual within
the sample/population.
Observation/Measurement the value of a
variable for an element. Data Set collection of values of one or more
variables.
Ungrouped data set contains information ofeach member of a sample or population.
Grouped data set collection of data set whichare grouped in classes.
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Variables Qualitative Variables
- classification based on some attribute or
characteristics.
- ex: gender, marital status, type of cars
Quantitative Variables
- numerical measures
- ex: weight, height, number of cars owned,
student marks
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Variables Quantitative Variables
(a) Discrete variablescountable / finite
number of possible values
(b) Continuous variablesinfinite number
and uncountable. Obtain by measuring;include fractions and decimals
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Graphical Methods Frequency distributions
Bar graph
Pie chart Histogram
Polygon
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Numerical Measures
Relationship between mean, mode & median
Measures of Central
Tendency
Measures of Dispersion
Mean Range
Median Variance
Mode Standard deviation
Skewness
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Measures of CentralTendency - POPULATION Mean
the average
Median
- value that lies in the middle
- Calculation : based on grouped or ungroupeddata.
Mode
- the most frequent observation of the variable
that occurs in the data set. Skewness
- the measure of asymmetry of the data set.
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Measures of Dispersion -POPULATION Range
- difference between the largest data value andthe smallest data value.
Variance- the difference between each observation andthe mean; based upon the deviation about themean.
Standard Deviation- how closely the values of the data set areclustered around the mean
- the spread of the distribution
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Mean
Variance
Standard deviation
POPULATION1 2 1...
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SAMPLINGReasons to sample:
To contact the whole population would be timeconsuming
The cost of studying the all items in populationmay be prohibitive
The physical impossibility of checking all items inthe population
The destructive nature of some tests
The sample results are adequate
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Measures of CentralTendency - SAMPLE Mean
Median
Mode
Skewness
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Measures of Dispersion -SAMPLE Range
Variance
Standard Deviation
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SAMPLE Mean
Variance
Standard deviation
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End For Today