Statistics and probability

• Range is the difference between the highest and lowest values in a set of numbers.
• Statistics: the practice or science of collecting and analysing numerical data in large quantities, especially for the purpose of inferring proportions in a whole from those in a representative sample
• Statistics


  The science of collecting, analyzing, presenting, and interpreting data
• Descriptive Statistics


  Analysis of data that helps describe, show, or summarize data in a meaningful way, such that, for example, patterns might emerge from the data
• Inferential Statistics


  Process of examining the relationships between variables within a sample and then make generalizations or predictions about how those variables will relate to a higher population
• Population


  Includes all the members of the group in which we want to analyze and draw conclusions
• Sample


  A part or a portion of the population selected for analysis
• Parameter


  A numerical measure of a characteristic of a population
• Statistic


  A numerical measure of a characteristic of a sample
• Sources of Data


  • Primary Data
  • Secondary Data
• Primary Data


  Data obtained from original, first-hand sources (can be taken from interviews, surveys, or experimentations)
• Secondary Data


  Data obtained from previously recorded data
• Constant


  A characteristic of data that does not vary (example is the boiling point of water which is constant at 100 degrees Celsius)
• Variable


  Characteristic of data that can take different value (example is weight of people and hair color)
• Classifications of Variables


  • Continuous Variables
  • Discrete Variables
• Continuous Variables


  Variables which can assume an infinite number of values (examples are height, temperature)
• Discrete Variables


  Variables which consist of a finite/countable number of values (example are number of family members)
• Types of Data


  • Qualitative Data
  • Quantitative Data
• Qualitative Data


  Also called as categorical variable; have values that describe a "quality" or "characteristic" of a data unit, and represented by a non-numeric value (examples are gender, occupation, eye color, etc.)
• Quantitative Data


  Also called as numerical variable; have values that describe a measurable quantity as a number (examples are height, weight, waist line, etc.)
• Levels of Measurement


  • Nominal Level
  • Ordinal Level
  • Interval Level
  • Ratio Level
• Nominal Level


  A measurement of categorical variable wherein values can be categorized but cannot be organized in a logical sequence
• Ordinal Level


  A measurement of categorical variables wherein values can be categorized and can be logically ordered or ranked
• Interval Level


  A measurement of numerical variables wherein values can be categorized, ranked, and evenly spaced but no true zero point
• Ratio Level


  Same characteristics as interval level of measurement but the main difference is that, it has a true zero point
• Nominal


  • sex (male & female), skin color, religion
• Ordinal


  • clothing size
• Interval


  • temperature
• Ratio


  • salary
• The difference between 2800C & 2900C, and 3300C & 3400C is the same which is 1 0C


  00C does not mean the absence of temperature
• 0 pesos


  Means there is literally no salary to receive
• Frequency Distribution


  A grouping of the data into categories showing the number of observations in each of the non-overlapping classes
• Raw Data


  Data collected in original form
• Range


  Difference of the highest value and the lowest value in a distribution
• Class


  Intervals of data entries
• Class Limits


  The highest and lowest values describing a class
• Interval (i)


  The distance between class lower boundary and class upper boundary
• Frequency (f)


  The number of values in a specific class of a frequency distribution
• Relative Frequency (rf)


  The value obtained when the frequencies in each class of the frequency distribution is divided by the total number of values
• Percentage


  Obtained by multiplying the relative frequency by 100%