STATISTICS
      Statistics is the science of collecting, analyzing, interpreting or explaining, and presenting data.
It can be employed to make an accurate decision.

• Collecting Data 
• Definition of data and datum
• Datum : facts needed
• Data : collection of several datum
• Definition of population and sample
• Population : all subjects being studied
• Sample : part of population being studied
• Type of data 
• Quantitative data : data in form of numbers
• Discrete data : data obtained by counting
• Continu data : data obtained by measuring
• Qualitative data : data not in form of number
• Methods in data collecting
• Interview
• Questionaire
• Observation
• Measures of Central Tendency
• Mean :  the "average" you're used to, where you add up all the numbers and then divide by the number of numbers.
• formula :     
• ∑$\sum$, represents the summation
  X, represents scores
  N, represents number of scores
• Combined Mean : 
• formula : 
• Median : the "middle" value in the list of numbers. To find the median, your numbers have to be listed in numerical order, so you may have to rewrite your list first.
• formula : 

                                           

• Mode : value that occurs most often. If no number is repeated, then there is no mode for the list.
• Measures of Dispersion 
• Range :  the difference between the largest and smallest values
• formula : R = biggest datum - smallest datum 
• Quartile (Q1, Q2, Q3)
• Q1 : middle number between the smallest number and the median of the data set
• Q2 : median of the data
• Q3 : the middle value between the median and the highest value of the data set
• formula (total number of the numbers(n) is an even number) : 
• formula (total number of numbers(n) is an odd number) : 
• Interquartile Range : measure of variability, based on dividing a data set into quartiles
• formula : QR : Q3 - Q1
• Semi Interquartile Range / Quartile Deviation : measure of spread or dispersion. It is computed as one half the difference between the 75th percentile [often called (Q3)] and the 25th percentile (Q1)
• formula :

                                        

• Presenting Statistical Data 
• Pictogram (pictorial graph)

                        

• Bar Chart

                  

• Line Chart 

                      

• Pie Chart