1. Introduction To Statistics

2. 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

3. 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

4. Descriptive or Inferential Statistics
The last four semesters an instructor taught Intermediate Algebra, the following numbers of people passed the class. SY SY
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.

5. Descriptive or Inferential Statistics
The last four semesters an instructor taught Intermediate Algebra, the following numbers of people passed the class. SY SY
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.

6. Descriptive or Inferential Statistics
The last four semesters an instructor taught Intermediate Algebra, the following numbers of people passed the class. SY SY
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.

7. Descriptive or Inferential Statistics
The last four semesters an instructor taught Intermediate Algebra, the following numbers of people passed the class. SY SY
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.

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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