1. After completion of the lesson you should be able to do
Define data and its types, sample and population
Describe survey, sample and population
Differentiate between qualitative and quantitative
data, discrete and continuous data, biased and valid
data
2.
3. Data are sets of information (facts, numbers, words and measurements)
collected through experiments, observations, surveys and interviews
4. Qualitative data (descriptive information)
deals with quality. It can be observed, but we
cannot measure
Quantitative data deals with quantity and
numbers, and it can be measured also called
Numerical Data
5. Qualitative Data Quantitative Data
Favorite Movie Volume of Coke Can i.e. 355 ml
Textures Number of cars sold
Favorite Color Number of girls in a class
6. Discrete data can only take certain values that is can be described in
whole numbers. For example number of students, number of car sold
Continuous Data can take any value for example length of a room
(15.7 meters), height (6.2 ft.)
7. In a census survey, data is collected from all the people in a population. For example, when every student
in a school is asked to name her/his favorite movie, this survey on the school’s Favorite Movie is a census
survey, and total number of students in school is the population in this case
8. In a sample survey, data is collected from a portion or a sample of a population. For example, when
only a few students in a school is asked to name her/his favorite movie, this survey on the
school’s favorite movie is a sample survey. A sample survey is less costly and requires less time
than census survey.
9. Sometimes, a graph shows a trend or relationship in the data. When you use
data to predict a value in the future, or to estimate a value between given data,
you make an inference. When you use data to make a conclusion you are inferring
something.
10. A sample is biased if it does not accurately represent the population
A survey is reliable if the result can be duplicated in another survey
A survey is valid if the result represent the population
For example, when only girls are surveyed to determine the school's favorite movie, the sample is biased
and the survey is not valid. This survey will be more reliable when data are collected from an approximately
equal number of boys and girls
