stats and prob

• Statistics is a branch of applied mathematics which deals with the collection, organization, presentation, analysis and interpretation of data.
• Descriptive Statistics - Summarizes or describes the important characteristics of a known set of data.
• Inferential Statistics - Consists of generalizing from samples to populations, performing hypothesis testing, determining relationships among variables, and making predictions.
• Population -consists of all members of a group being studied
• Sample -is a portion or part, of the population of interest selected for analysis
• Parameter -a numerical index describing a characteristic of a population
• Statistic - a numerical index describing a characteristic of a sample
• Parameter- The mean monthly income of your target market
• Statistic- The mean monthly income of 60 of your regular customers
• Primary Data are data that come from an original source, and are intended to answer specific research questions. It can be taken by interview, mailin questionnaire, survey, or experimentation.
• Secondary Data -are data that are taken from previously recorded data, such as information in research conducted, industry financial statements, business periodicals, and government reports.
• Qualitative Variable (Categorical Variable)- are classified according to some attributes or categories.
• QUALITATIVE- Marital Status & Gender
• Quantitative Variable (Numerical Variable)- are variables that are classified according to numerical characteristics.
• Quantitative- Number of child & Age
• Experimental Classification – A research may classify variables according to purpose whether experimental or mathematical.
• Continuous Variable- can assume any of an infinite numbers of values
• Discrete Variable- consist of either a finite number of values or countable number of values
• Continuous Variable- Voltage, Weight, Wind speed
• Discrete Variable- Number of sales in a week & Number of Senators
• Categorical- Nominal & Ordinal
• Numerical- Interval & Ratio
• Nominal Level - classifies data into various distinct categories in which no ranking is implied. It indicates distinction.
• Nominal Level - Gender & hair color
• Ordinal- classifies data into distinct categories in which ranking is implied.
• Interval data- can include numerical data that does not use zero as a reference, such as age ranges, income ranges, IQ score ranges, temperature ranges, time spent, date ranges, and similar range-based data.
• Ratio data- can include variables like income, height, weight, annual sales, market share, product defect rates, time to repurchase, unemployment rate, and crime rate.