Statistics for Business

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