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In statistics, understanding the concepts of 'population' and 'sample' is fundamental.
The **population** refers to the complete set of elements (individuals, objects, or events) sharing some common characteristic. For example, all passengers aboard the Titanic make up the population in a given study.
On the other hand, a **sample** is a subset selected from the population for the purpose of study. This subset should ideally represent the population’s characteristics as closely as possible.
A study often uses samples to make inferences about the larger population, due to the impracticality of examining every member of a large population.
In the context of our Titanic scenario, since the study covered every single one of the 2223 passengers, this represents the whole population.
Thus, any numerical value derived from this study, describing a feature of these passengers, is a parameter.

Classifying data correctly is key to effective analysis.
Data can broadly be categorized into qualitative and quantitative.
**Qualitative data** (or categorical data) is descriptive and characterizes attributes or properties, such as names or labels. For instance, the categories of passenger classes on the Titanic (first, second, third) are qualitative.
**Quantitative data** represents numerical values and measures quantities. This can further be divided into discrete and continuous data.
- **Discrete data** consists of countable values, like the number of passengers.
- **Continuous data**, however, can take any value in a range, such as the readings of temperature or height.
Understanding these classifications helps in choosing the right statistical methods for analysis.
In the study of Titanic passengers, identifying these classifications allows better interpretation of the data.

Familiarity with statistical terms is crucial for interpreting data and drawing accurate conclusions. Let’s break down a few essential terms:
- **Parameter**: A numerical value summing up a characteristic of the population. In our Titanic study, the total number of passengers (2223) is a parameter since it’s derived from the entire population.
- **Statistic**: A numerical value summarizing a characteristic of a sample drawn from the population. If we had surveyed only a group of 300 passengers instead of the whole group, any value describing that group would be a statistic.
- **Variable**: A characteristic or attribute that can take different values. For example, the age of Titanic passengers is a variable.
- **Mean**: The average of a set of values, calculated by dividing the sum of the values by their count. For instance, to find the average age of Titanic passengers, we’d add up the ages and divide by the number of passengers.
- **Median**: The middle value in a data set when it's ordered from smallest to largest.
By clearly understanding these terms and their application, students can confidently tackle any statistical problem.