Types of data
There are two main types of data:
Quantitative
The answer is a number. Examples: number of brothers, height,....
Quantitative data can be discrete or continuous:
"Discrete data" has an exact value. Example: number of brothers.
"Continuous data" can take any value, or it may be between two possible values. An example is the height.
Qualitative
The answer is a word. Examples: hair's colour, civil status,....
Population an sample
All statistic study refers to a group of people or things called population.
The population's components are called individuals.
As it is not always possible to observe the total population, a part of the population is chosen.
It is called sample and the sample's election is very important
because it has to be representative of the total population.
The number of elements in a sample is called size.
EXAMPLES:
Situation: You are carrying out a survey on homework. You have to select a sample and ask 100 students.
There are (POPULATION):
1 ESO 
80 
2 ESO 
100 
3 ESO 
140 
4 ESO 
80 
Calculate the number of students you will ask for each group (the sample)
Total = 80+100+140+80=400
SAMPLE:
1 ESO 
20 
2 ESO 
25 
3 ESO 
35 
4 ESO 
20 
