Nature of Probability and Statistics Essay

Descriptive statistics consists of the collection, organization, summarization, and presentation of info. Inferential statistics consists of generalizing from samples to populations, performing estimations hypothesis testing, determining relationships among variables, and making predictions. (Probability, Hypothesis testing, relationships between variables, predictions) Probability is the pass of an event occurring. A population consists of all subjects that argon being studied. A sample is a group of subjects selected from a population.Variables and Types of Data In order to pile up knowledge about seemingly haphazard events, statisticians collect information for variables that describe the events. A variable is a characteristic or attribute that heap copy different values. 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 variables have values that are determined by ru n into. 1 M227 Chapter 1 genius of Probability and StatisticsQualitative variables can be placed into distinct categories according to some characteristic or attribute. Quantitative variables are numerical in personality and can be ordered or ranked. Quantitative variables can be further classified into two groups. o Discrete variables assume values that can be counted. o Continuous variables can assume all values between any two specific values. (Discuss boundaries ex. recorded height of 73 has demarcation of 72. 5 ? x 73. 5 ) Levels of MeasurementVariables are classified by how are organized, counted, or measured Nominalclassifies data into mutually exclusive (nonoverlapping), tucker out categories in which no order or ranking can be imposed on the data. Ordinalclassifies data into categories that can be ranked however, microscopic differences between the ranks do not exist. Intervalranks data, and precise differences between units of measure do exist however, there is no me aningful zero. Ratiopossesses all the characteristics of time interval measurement, and there exists a true zero. Data Collection and Sampling TechniquesSurveys are the most common method of collecting data. Three methods of surveying are o Teleph angiotensin converting enzyme 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. cardinal main ways to classify statistical studies In an observational study, the researcher merely observes what is happening or what has happened in the pa st 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 other variables. 2 M227 Chapter 1 Nature of Probability and Statistics Statistical studies usually include one or more independent variables and one dependent variable.The independent variable in an axperimental study is the one that is being manipulated by the researcher. The independent variable is in any case 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 orgasm of calculators, numerical computations became easier. Excel, MINITAB, and the TI-83 graphing calculator can be used to perform statistical compu tations.