Nature of Probability and Statistics Essay

Descriptive statistics consists of the collection, organization, summarization, and presentation of data. Inferential statistics consists of generalizing from prototypes to universe of discourses, performing estimations meditation testing, determining relationships among variables, and making predictions. (Probability, Hypothesis testing, relationships in the midst of variables, predictions) Probability is the chance of an termination occurring. A world consists of all subjects that are being studied. A sample is a group of subjects selected from a population.Variables and Types of Data In order to put one across knowledge about seemingly haphazard events, statisticians collect information for variables that hound the events. A variable is a characteristic or attribute that dejection assume different think ofs. Data are the values that variables can assume. A data set is a collection of data values. Each value in the data set is called a data value or a datum. Random varia bles have values that are determined by chance. 1 M227 Chapter 1 Nature of Probability and StatisticsQualitative variables can be placed into distinct categories according to some characteristic or attribute. denary variables are numerical in nature and can be say or graded. Quantitative variables can be further classified into deuce groups. o Discrete variables assume values that can be counted. o Continuous variables can assume all values between individually two specific values. (Discuss boundaries ex. recorded height of 73 has boundary of 72. 5 ? x 73. 5 ) Levels of MeasurementVariables are classified by how are organized, counted, or measured Nominalclassifies data into mutually exclusive (nonoverlapping), weary categories in which no order or ranking can be imposed on the data. Ordinalclassifies data into categories that can be ranked however, precise differences between the ranks do not exist. Intervalranks data, and precise differences between units of measure do exis t however, there is no meaningful zero. proportionalitypossesses all the characteristics of interval measurement, and there exists a true zero. Data order of battle and Sampling TechniquesSurveys are the most common method of collecting data. lead methods of surveying are o Telephone surveys o Mailed questionnaire surveys o Personal interviews Direct Observations or surveying records Methods to obtain unbiased samples o Random samples are selected using chance methods or random methods. o Systematic samples are obtained by numbering each subject of the population and then selecting every kth number. o Stratified samples are obtained by dividing the population into groups according to some characteristic that is important to the study, then sampling from each group. Cluster samples are obtained by using intact groups called clusters. Two primary(prenominal) ways to classify statistical studies In an observational study, the researcher nevertheless observes what is happening or wh at has happened in the past and tries to draw conclusions based on these observations. In an experimental study, the researcher manipulates one of the variables and tries to determine how the manipulation influences new(prenominal) variables. 2 M227 Chapter 1 Nature of Probability and Statistics Statistical studies usually involve one or more sovereign variables and one dependent variable.The autarkic variable in an axperimental study is the one that is being manipulated by the researcher. The independent variable is also called the explanatory variable. The rsultant variable is called the dependent variable or the random outcome. Uses and Misuses of Statistics Detached statistics Implied connections Misleading graphs Faulty survey questions Computers and Calculators In the past, statistical calculations were done with pencil and paper. However, with the advent of calculators, numerical computations became easier. Excel, MINITAB, and the TI-83 graphing calculator can be used to perform statistical computations.