Data collected in original form is called raw data

Data can be classified into two types

**Categorical data:**Qualitative data, usually collected through observation and is descriptive. E.g. colour, texture, etc.**Numerical data:**Quantitative data consisting of numerical values.

There are 2 types of numerical data:

**Discreet data:**- It is data based on counts, it is data that can be associated with a specific value.
- Bar graph represents discreet data only

**Continuous data:**- Data representing series of values or values grouped into categories.
- Histogram represents continuous data.

A frequency distribution is the organisation of raw data in table form, using classes and frequencies.

The data can be placed in categories and organized in categorical frequency distributions.

- Example:

- A survey can be used to gather information about a group. Often, a part of the group, called a
**sample**, is chosen to represent the whole group or population - A sample must represent the population fairly. In a random sample, each person in the population has an equal chance of being chosen.
- A
**statistic**is**biased**if it is calculated in such a way that it is systematically different from the population parameter being estimated eg when certain individuals are being more likely to be selected than others. - An estimator or decision rule with zero
**bias**is called**unbiased**. - Analysing information involves identifying and describing trends(patterns in data represented in tables/graphs and explain what the data indicates about the question/problem for which the data was collected.

MooMooMath & Science. (2016). Discrete and continous data (Standard YouTube licence)

365 Data Science. (2019). Types of data: Categorical vs numerical (Standard YouTube licence)

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