A **population parameter** in statistics describes a group or population. Population parameter is a fixed, but unknown characteristic describing the distribution for all values of an entire group. This should not be confused by parameters in other types of math. These are values that are constant for a mathematical function. A population parameter is not a statistic. This is data that refers only to a subset of a particular population. A well-designed study can help you to calculate the true population value.

### Population Parameter: Key Takeaways

- A sample is an individual or part of a population.
- A sample statistic can provide an accurate estimate of the population parameter if it is well-designed.
- A population is a group of people or objects that includes all of them. Depending on the subject matter, a population can be large and small.
- Parameters are data that describe the entire population. Statistics, on the other hand, is data that only describes a subset of that population.

### What is a Population?

A population is a collection of all members in a group. Depending on the topic you are studying, a population could be small or large. A population could include “all residents of Germany”, which was about 83 million people in 2017, or “all freshman at a particular high school,” which can vary from one person to several thousand, depending on the school.

Although you might have heard the word “population” used to refer to people, it can also be used to describe other types of things. You might be interested in the population of birds living near a particular beach, or the balloons made by a particular manufacturer.

### Population vs. Sample

A sample is a *subset* or *portion* of a population, regardless of how small or large it may be. If there are 100 freshmen in a high-school class, you might choose to only study 45.

Statistics studies are often conducted using samples rather than populations. This is because it can be expensive, time-consuming, or impossible to reach all members of a population. However, you should design your statistical study to accurately represent the population. You might want to randomly choose people from all parts of Germany if you are looking for a representative sample of all Germans.

Also, ensure that your sample (or number of items you are studying) is sufficient to make your data statistically significant. It accurately estimates the true statistics about a population.

### What is a Parameter?

Parameters in math are constant values that are used to define a mathematical function. Parameters are different in statistics. Parameter is data that describes a *whole population*. A population parameter could be the 35 percent of lunches brought home by students at X high school on a given day.

### Parameter vs. Statistic

Parameters and statistics have a lot in common. They both tell something about a group, such as that 20% of M&Ms are red. But the main difference is *who* and *what* are they describing. Parameters refer to the *whole* population. Statistics refer to the *portion* or the *sample* that was studied in a study.

In the example above, you might count the number of red M&Ms contained in multiple packs. This will give you your *statistic*. The statistic you get should accurately reflect the population parameter if your study was well designed.