## Key Concepts

Review core concepts you need to learn to master this subject

Mean of a Dataset

Mean of a Dataset

The *mean*, or average, of a dataset is calculated by adding all the values in the dataset and then dividing by the number of values in the set.

For example, for the dataset `[1,2,3]`

, the mean is `1+2+3`

/ `3`

= `2`

.

- 1Finding the center of a dataset is one of the most common ways to summarize statistical findings. Often, people communicate the center of data using words like,
*on average*,*usually*, or*often*…. - 2The
*mean*, often referred to as the*average*, is a way to measure the center of a dataset. The average of a set is calculated using a two-step process: 1. Add all of the observations in your da… - 3While you’ve shown that you can calculate the average yourself, it becomes time-consuming as the size of your dataset increases — imagine adding all of the numbers in a dataset with 10,000 ob…
- 4In this lesson, you learned how to calculate the average of a dataset using the formula: \bar{x} = \frac{x_1 + x_2 … + x_{n}}{n} and the NumPy function: np.average(my_array) — Circling back…

- 1In this lesson, you will learn how to find the
*median*of a dataset — a common measure of a dataset’s center. Each of the next three exercises will cover the following topics: - Manually fin… - 2The formal definition for the median of a dataset is: *The value that, assuming the dataset is ordered from smallest to largest, falls in the middle. If there are an even number of values in a dat…
- 3Finding the median of a dataset becomes increasingly time-consuming as the size of your dataset increases — imagine finding the median of an unsorted dataset with 10,000 observations. The Nu…
- 4In this lesson, you learned how to find the median of a dataset in two steps: 1. Sort the dataset 2. Identify the one or two numbers that fall in the middle of the sorted dataset You also learned …

- 1In this lesson, you will learn how to find the
*mode*of a dataset. Each of the next three exercises will cover the following: - Manually finding the mode of a dataset - Using Python’s SciPy librar… - 2The formal definition for the mode of a dataset is: *The most frequently occurring observation in the dataset. A dataset can have multiple modes if there is more than one value with the same maxim…
- 3Finding the mode of a dataset becomes increasingly time-consuming as the size of your dataset increases — imagine finding the mode of a dataset with 10,000 observations. The SciPy stats.mode…
- 4In this lesson, you learned how to find the mode of a dataset in two steps: 1. Find the frequency of every unique number in the dataset 2. Determine which number has the highest frequency You also…

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