data management

• Statistical packages are collections of software designed to aid in statistical analysis and data exploration
• Statistics is that branch of science which deals with the collection, presentation, analysis, and interpretation of data
• General Uses of Statistics

  1. Statistics aids in decision making
  2. Statistics summarizes data for public use
• Statistical Methods of Applied Statistics – refer to procedures and techniques used in the collection, presentation, analysis and interpretation of data.
• Statistical Theory of Mathematical Statistics – deals with the development and exposition of theories that serve as bases of statistical methods
• Descriptive Statistics methods concerned with the collection, description, and analysis of a set of data without drawing conclusions or inferences about a larger set
• Descriptive Statistics conclusions apply only to the data on hand
• Inferential Statistics methods concerned with making predictions or inferences about a larger set of data using only the information gathered from a subset of this larger set
• Inferential Statistics conclusions are applicable to a larger set of data which the data on hand is only a subset
• A population is a collection of all the elements under consideration in a statistical study.
• A sample is a part or subset of the population from which the information is collected.
• A parameter is a numerical characteristic of the population.
• A statistic is a numerical characteristic of the sample
• variable is a characteristic or attribute of persons or objects which can assume different values or labels for different persons or objects under consideration.
• Measurement is the process of determining the value or label of a particular variable for the particular experimental unit.
• experimental unit is the individual or object on which a variable is measured.
• Discrete Variable - a variable which can assume finite, or, at most, countable infinite number of values; usually measured by counting or enumeration.
• Continuous Variable - a variable which can assume infinitely many values corresponding to a line interval
• Qualitative variable - a variable that yields categorical responses (e.g., political affiliation, occupation, marital status)
• Quantitative variable- a variable that takes on numerical values representing an amount or quantity (e.g., weight, height, no. of cars)
• nominal level is the weakest level of measurement where numbers or symbols are used simply for categorizing subjects into different groups.
• ordinal level of measurement contains the properties of the nominal level, and in addition, the number assigned to categories of any variable maybe ranked or ordered in some low-to-high-manner.
• interval level is that which has the properties of the nominal and ordinal levels, and in addition the distance between any two numbers on the scale are of known sizes
• ratio level of measurement contains all the properties of the interval level, and in addition, it has a “true zero” point.
• Primary data - data measured by the researcher/agency that published i
• Secondary data - any republication of data by another agency
• Internal Data - information that relates to the operations and functions of the organization collecting the data.
• External Data - information that relates to some activity outside the organization collecting the data
• Survey Method - questions are asked to obtain information, either through self-administered questionnaire or personal interview
• Observation Method - makes possible the recording of behaviour but only at the time of occurrence
• Experimental Method - a method designed for collecting data under controlled conditions.
• Use of existing studies - e.g., census, health statistics, and weather bureau reports
• documentary sources – published or written reports, periodicals, unpublished documents, etc.
• field sources – researchers who have done studies on the area of interest are asked personally or directly for information needed
• Registration Method - e.g., car registration, student registration, and hospital admission
• Census or complete enumeration is the process of gathering information from every unit in the population.
• Survey sampling is the process of obtaining information from the units in the selected sample.