Introduction To Statistics

Statistics branch of applied mathematics that deals with the collection, organization or presentation, analysis and interpretation of data Collection – gathering of data or information Organization or Presentation – summarizing data or information into textual, graphical or tabular forms Analysis – describing the data by using statistical methods and procedures Interpretation – process of making conclusions based on the analyzed data

Fields of Statistics Descriptive Statistics Inferential Statistics concerned with the methods of collecting, organizing and presenting data appropriately and creatively to describe or assess group characteristics Inferential Statistics concerned with inferring or drawing conclusions about the population based from pre-selected elements of the population

Descriptive or Inferential Statistics The last four semesters an instructor taught Intermediate Algebra, the following numbers of people passed the class. SY 06 - 07 SY 07 - 08 1st Sem 2nd Sem 17 19 4 20 a) The last four semesters the instructor taught Intermediate Algebra, an average of 15 people passed the class. b) The next time the instructor teaches Intermediate Algebra, we can expect approximately 15 people to pass the class.

Descriptive or Inferential Statistics The last four semesters an instructor taught Intermediate Algebra, the following numbers of people passed the class. SY 06 - 07 SY 07 - 08 1st Sem 2nd Sem 17 19 4 20 c) This instructor will never pass more than 20 people in an Intermediate Algebra class. d) The last four semesters the instructor taught Intermediate Algebra, no more than 20 people passed the class.

Descriptive or Inferential Statistics The last four semesters an instructor taught Intermediate Algebra, the following numbers of people passed the class. SY 06 - 07 SY 07 - 08 1st Sem 2nd Sem 17 19 4 20 e) Only 4 people passed one semester because the instructor was in a bad mood the entire semester. f) The instructor passed 20 people the last time he taught the class to keep the administration off of his back for poor results.

Descriptive or Inferential Statistics The last four semesters an instructor taught Intermediate Algebra, the following numbers of people passed the class. SY 06 - 07 SY 07 - 08 1st Sem 2nd Sem 17 19 4 20 g) The instructor passes so few people in his Intermediate Algebra classes because he doesn't like teaching that class.

Terminologies in Statistics Population entire set of individuals or objects of interest Sample a portion or part or subset of a population Parameter any numerical value describing a characteristic of a population Statistic any numerical value describing a characteristic of a sample (estimate of a parameter) Parameter Population Statistic Sample

Terminologies in Statistics Data facts concerning things such as status in life of people, defectiveness of objects or effect of an event to the society Qualitative Data data which can assume values that manifest the concept of attributes (categorical data) Quantitative Data data which are numerical in nature and subjected for computations

Terminologies in Statistics Information set of data that have been processed and presented in a form suitable for human interpretation, usually with a purpose of revealing trends or patterns about the population processed Data Information Constant characteristic or property of a population or sample which makes the members of the group similar to each other Variable characteristic or property of a population or sample which makes the members different from each other

Classification of Variables Discrete Variable one that can assume a finite number of values Continuous Variable one that can assume infinite number values within a specified interval Dependent Variable affected or influenced by another variable Independent Variable affects or influences the dependent variable

Classification of Variables Dichotomous Variable observations about this variable can be made only in two categories Multinomial Variable observations about this variable can be made in more than two categories

Levels of Measurement Nominal Level Ordinal Level lowest or weakest level of measurement where symbols are used simply for categorizing subjects into different groups example: nationality, gender Ordinal Level contains the properties of the nominal level, and in addition, the numbers assigned to categories of any variable may be ranked example: size of shirt, students rank in the class

Levels of Measurement Interval Level Ratio Level has the properties of the nominal and ordinal levels, and in addition, the distance between any two numbers on the scale are known sizes example: I.Q. scores Ratio Level contains the properties of the first three levels, and in addition, there is a “true zero” point example: age, speed of a car