Business statisticsabm-403

Presented by:

Hina Varshney

B.Com IV Sem

12D012

TOPIC: Statistical Error, Enquiry, Census vs. Sample Method Of

Investigation

Statistical Error• Sampling is a technique which helps us in

understanding the parameters or characteristics of the universe or population by examining only a small part of it.

• Statistical data are obtained either by measurement or by observation; hence it is not possible to ensure perfect accuracy.

• For e.g., in a population census, it cannot be said that not a single person is left out. It is also not possible to assure absolute accuracy while making estimates about a population from investigation of a sample. These inaccuracies are called Errors in Statistics.

Types of Statistical Errors

• There are two types of statistical error:

Sampling errors

Non- sampling errors

Sampling Errors• These arise due to drawing faulty

inferences about the population based upon the results of the samples. In other words, it is the difference between the results that are obtained by the sample study and entire population.

• For example, If a sample study indicates that 25% of the adult population of a city does not smoke and the study of the entire adult population of a city indicates that 30% are non smokers, then this difference would be considered as the sampling error.

REASONS OF SAMPLING ERRORS• Errors of origin: errors arise on account

of inappropriate data, defective questionnaire.

• Errors of inadequacy: related to incomplete data.

• Errors of interpretation: errors committed by statistician due to inadequate knowledge.

• Errors of manipulation: these are concerned with clerical errors, arithmetical slips.

Categories of sampling errors• Biased errors: arise due to biased or

prejudice attitude of the informants, enumerator or investigator in selecting ,estimating, or measuring instruments.

• Unbiased errors: arise in the normal course of investigation or enumeration on account of chance. These errors can be avoid or removed with proper planning of statistical investigations.

NON SAMPLING ERRORS

• Non-sampling errors are introduced due to technically faulty observations or during the processing of data. These errors could also arise due to defective methods of data collection, incomplete coverage of the population because some units of the population are not available for study.

• For e.g.. Counting of illiterate person in state.

STATISTICAL ENQUIRY

• Statistical enquiry refers to search for the collection of facts of a given problem. The collected data are the raw material, through which the problem is to be studied. The relevant collection of information by any agency to tackle a particular problem under study is termed as surveyor enquiry.

CENSUS V/S SAMPLE• It is obvious that when whole population is

taken into account, data collection is called Census Method, whereas when a small group that is representative of the entire population is used, it is called a Sample Method.

• Census is very time consuming and expensive, whereas sampling is quick and inexpensive.

CENSUS V/S SAMPLE• Data from census is reliable and

accurate, there is a margin of error in data obtained from sampling.

• Census refers to periodic collection of information about the population from the entire population. Sampling is a method of collecting information from a sample that is representative of entire population

References• DEI Study Material

• http://bhanusigdel.wordpress.com/2011/11/17/census-and-sampling-method/

• JHAWAHAR PUBLICATION

• Sahitya bhawan: Statistics by B.N Gupta