AbstractStatistics is a science that provides precise techniques for collecting and sortinginformation made easy by tools and methods for further analysis.The object of descriptive statistics, from sample data, is to describe the most importantcharacteristics, by which we refer to those amounts that provide information on the topicof interest which we are studying.& 2009 Published by Elsevier Espan˜a, S.L.Introduction (using descriptive analysis)Statistics is the set of procedures and techniques used tocollect, organise and analyse data, which are the basis formaking decisions in situations of uncertainty. Statistics aredivided into descriptive and inferential.Descriptive statistics refers to the collection, presentation,description, analysis and interpretation of datacollection. Its purpose is to summarize these from a set ofvalues. Descriptive statistics is the method of obtaining dataset conclusions about themselves. It can be used tosummarise or describe any data set, either a population ora sample.Inferential statistics refers to the set of techniques usedto gain conclusions from the population through manipulationof the sample data. It is the process of makinggeneralisations about the population from a representativesample of data.Inference distinguishes parameter estimation and hypothesistesting. The statistical analysis is the whole process oforganisation, processing, reduction and interpretation ofdata to make inferences.When analysing data from a sample, the most importantthing is the presentation of numerical and graphical summariesof the information. These summaries represent characteristicsof the sample. This is what we call ‘‘statistics’’. Thereare a variety of numerical and graphical summaries that canbe calculated with data from the sample. Each of theseprovides a description of some aspect of self-interest.The reasons to study samples instead of populations arediverse and among them we can point out:
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