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What is Statistics
Statistics ( pl. ) –numbers, graphics, tables etc.
Statistics ( sg.) – science, subject of study
Statistics is a support of Economics, a tool of Management, dealing with the collection, analysis, interpretation and presentation of masses of numerical data
What is Statistics
Statistics is a way of getting information from data studying large collectivities/populations
Large collectivities – variation
What is variation - a deviation in structure or character from others of the same collectivities
What is Statistics
Statistics determine stable characteristics - statistical/stochastic law
Statistical law – can be applied only for the whole collectivity.
Stochastic vs deterministic
Descriptive vs Inferential
Descriptive statistics involves the arrangement, summary, and presentation of data, to enable meaningful interpretation, and to support decision making.
Descriptive statistics methods make use of
graphical techniques
numerical descriptive measures.
The methods presented apply to both
the entire population
the sample
Descriptive vs Inferential
Inferential Statistics – a set o procedures used to make predictions about a whole population by studying the properties of a population sample or to forecast
Basic Concepts of Statistics
Population - the total of any kind of units under consideration by the statistician
Sample - any portion of the population, selected for study
A parameter is a characteristic of a population
A statistic is a characteristic of a sample
Basic Concepts of Statistics
Variable( characteristic ) - a characteristic of population or sample that is of interest for us.
The waiting time for medical services
Capital expenditure
Grade
Data - the actual values of variables
Basic Concepts of Statistics
Non-numerical/qualitative variable – words – CATEGORIAL VARIABLE
Marital Status
Single/Married/Divorced/Widowed
Search engine
Google/Yahoo/Netscape/AOL/MSN/Other
Numerical/quantitative variables
-have units of measurement ( dollars, years, etc.)
- Quantitative variables can be :
- discrete
- continuous
Quantitative variables
Continuous variable – a quantitative variable that has an infinite number of possible values that are not countable.
Discrete variable – a quantitative variable that has either a finite number of possible values or a countable number of possible values
Types of data
What are data – systematically recorded information ( numbers, words, labels, codes ) together with context
Data is useless without context
Context :
- WHO was measured
- WHAT was measured
- WHERE data were collected
- WHEN data were collected
- WHY study was performed
- HOW data were collected
Measurement Levels
Nominal scale
- symbols, codes, labels
The role is to identify - allowing grouping the units into classes
Ex. Gender, color etc.
Ordinal scale – symbols allowing grouping and ranking the units
- Ex. Education level
Conținut arhivă zip
- Statistics for Business.ppt
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