25-01-2013, 04:21 PM
What is Statistics
Statistics.PPT (Size: 66.5 KB / Downloads: 22)
What is Meant by Statistics?
Statistics is the science of collecting, organizing, presenting, analyzing, and interpreting numerical data for the purpose of assisting in making a more effective decision.
Who Uses Statistics?
Statistical techniques are used extensively by marketing, accounting, quality control, consumers, professional sports people, hospital administrators, educators, politicians, physicians, etc...
Types of Statistics
Descriptive Statistics: Methods of organizing, summarizing, and presenting data in an informative way.
EXAMPLE 1: A Gallup poll found that 49% of the people in a survey knew the name of the first book of the Bible. The statistic 49 describes the number out of every 100 persons who knew the answer.
EXAMPLE 2: According to Consumer Reports, Whirlpool washing machine owners reported 9 problems per 100 machines during 1995. The statistic 9 describes the number of problems out of every 100 machines.
Inferential Statistics: A decision, estimate, prediction, or generalization about a population, based on a sample.
A population is a collection of all possible individuals, objects, or measurements of interest.
A sample is a portion, or part, of the population of interest.
Types of Variables
Quantitative variable: the variable can be reported numerically.
EXAMPLE: balance in your checking account, minutes remaining in class, number of children in a family.
Quantitative variables can be classified as either discrete or continuous.
Discrete variables: can only assume certain values and there are usually “gaps” between values.
EXAMPLE: the number of bedrooms in a house. (1,2,3,..., etc...).
Sources of Statistical Data
Researching problems usually requires published data. Statistics on these problems can be found in published articles, journals, and magazines.
Published data is not always available on a given subject. In such cases, information will have to be collected and analyzed.
One way of collecting data is via questionnaires.