Statistics

• Statistics


  A group of methods used to collect, analyze, present, and interpret data and to make decisions
• Educated guesses


  Decisions made by using statistical methods
• Pure guesses


  Decisions made without using statistical or scientific methods
• Mathematical statistics


  deals with the development, derivation, and proof of statistical theorems, formulas, rules, and laws
• Applied statistics


  involves the application of those theorems, formulas, rules, and laws to solve real-world problems
• Descriptive statistics


  consists of methods for organizing, displaying, and describing data by using tables, graphs, and summary measures
• Inferential statistics


  consists of methods that use sample results to help make decisions or predictions about a population from a sample
• Biostatitstics


  is the branch of applied statistics directed toward applications in the health sciences and biology
• Element


  is a specific subject of object about which the information is collected
• Variable


  is a characteristic under study that assumes different values of different elements
• Observation


  is the value of a variable for an element
• Data set


  is a collection of observations on one or more variables
• Univariate data


  results when a single variable is measured
• Bivariate data


  results when a two variable are measured
• Multivariate data


  results when a more than two variables are measured
• Population


  the collection of all elements–individuals, items, or objects–whose characteristics are being studied
• Sample


  the collection of a number of elements selected from a population
• Census


  the collection of information that includes every member of the population
• Sample survey


  the collection of information from the elements of a sample
• Parameter


  a numerical measure that summarize data for an entire population
• Statistic


  a numerical measure that summarize data from a sample
• Random sampling


  a method of sampling in which each member of the population has some chance of being selected in the sample
• Nonrandom sampling


  a method of sampling in which some member of the population may not have any chance of being selected in the sample
• Convenience sampling


  the most accessible members of the population are selected to obtain the results quickly
• Judgment sampling


  the members are selected from the population based on the judgment and prior knowledge of an expert
• Sampling error


  a statistical error that occurs when an analyst does not select a sample that represents the entire population of data
• Nonsampling errors


  . These are the errors that occur in the collection, recording, and tabulation of data. Such errors occur because of human mistakes and not chance.
• Selection error


  the error that occurs because the sampling frames is not representative of the population
• Sampling frame


  This list of members of the population that is used to select a sample.
• Nonresponse error


  the error that occurs because many of the people included in the sample do not respond to a survey
• Response error


  occurs when people included in the survey do not provide correct answers
• Voluntary response error


  occurs when a survey is conducted on a randomly selected people but on a questionnaire published in a magazine or newspaper and people are invited to respond to that questionnaire
• Simple random sampling


  a sampling technique in which any particular sample of a specific sample size has the same chance of being selected as any other sample of the same size
• Sample size


  is the number of elements in the sample
• Fishbowl sampling

  If we need to select 5 students from a class of 50 (target population), we write each of the 50 names on a separate piece of paper. Then, we place all 50 names in a bowl and mix them thoroughly. Next, we draw 1 name randomly from the bowl. We repeat this experiment four more times.
• Systematic random sampling


  s a sampling technique in which the elements of the sample are taken from every kth element in the population arranged alphabetically or by other characteristic
• Stratified random sampling


  a sampling technique in which the entire population is divided into smaller groups that are not overlapping and represent the entire population
• Cluster sampling


  a sampling technique in which the entire population is divided into multiple groups usually by geographical area
• Quantitative variable


  variables that can be measured numerically
• Discrete variable


  a variable whose values are countable with no possible intermediate values between consecutive values