stat101

• Statistics is a branch of science that deals with the Collection, Organization, Analysis, Interpretation, and Presentation of data
• Statistics is in the Formal Sciences branch
• The elements of a population are those we want to study
• We want to study variables from the elements
• The two fields of statistics are theoretical/mathematical and applied statistics
• descriptive statistics describe the data in hand
• inferential statistics infer characteristics of population using sample data
• measurement is the process of determining the value or label of the variable based on what has been observed
• qualitative variable is a variable that yields categorical responses
• quantitative variable is a variable that takes on numerical values representing an amount or quantity
• two kinds of quantitative variables are discrete and continuous variables
• discrete variable is a variable that is finite
• continuous variable is infinitely many values
• the four levels of measurement are nominal, ordinal, interval and ration
• common methods of data collection are: use of documented data, survey method, experiment, observation method, internal data, registration data, and computer simulation
• use of documented data: obtained from previous studies of individuals or private agencies
• survey method is a method of collecting data by asking people questions
• when the data came from a population, the study is called a census
• if the data came from a sample, the study is called a sample survey
• the questionnaire contains all the questions asked in a survey
• personal interview: interviewers personally ask the respondents and record their answers on the questionnaire
• telephone interview: interviewers ask the respondents through the telephone
• Using self-administered questionnaires: respondents fill up the questionnaires themselves without any assistance from an interviewer
• on-line surveys: respondent reads the questions and sends his responses via the internet or email
• experiment is a method of collecting data where there is direct human intervention on the conditions that may affect the values of the variable of interest
• explanatory variables are the variables in the study whose values are believed to have an effect on the value of the response variables
• extraneous variables: other variables that can give a different effect on the experiment
• observation method is a method of collecting data on the phenomenon of interest by recording the observations made about the phenomenon as it actually happens
• internal data are data generated from the operation and administration of the researcher's company
• registration data are data generated by other agencies or organizations through the process of registration as required by some law
• computer simulation makes use of a special kind of a mathematical formula called a statistical model that computes for values of the variable of interest
• complete enumeration, also known as census
• target population is the population we want to study
• sampled population is the population from where the sample is actually selected
• elementary unit or element is a member of the population whose measurement on the variable of interest is what we wish to examine
• sampling unit is the unit of the population that we select in our sample
• sampling frame is a list or map showing all the sampling units in the population
• sampling error is the error attributed to the variation present among the computed values of the statistic from the different possible samples consisting of n elements
• non-sampling error is the error from other sources apart from sampling fluctuation such as measurement errors and coverage errors
• Probability Sampling: method of selecting a sample wherein each element

  of the population has a known, nonzero chance of being included in the

  sample.