Measures of Center: Mean, Median, Mode

There are four main aspects to analyzing Quantitative data.

1. Measures of Center
2. Measures of Spread
3. The Shape of the data
4. Outliers

Let’s focus on ‘Measures of Center’ in this post: Mean, Median, Mode.
1. Mean

•  the average/ the expected value in mathematics.
• can be calculated as
• the sum  of all values / n (number of values in the dataset)

2. Median

• splits our data so that 50% of our values are lower and 50% are higher
• excludes outliers so it could be a more accurate measure if there is an outlier
• sort all the data in an incremental order and find the middle value
• if no. of dataset is odd — the direct middle
• if no. of dataset is even — the average of the two values in the middle

3. Mode

• the most frequent number in the data set
• no mode: if all observations in our dataset are observed with the same frequency
• (1,1,2,2,3,3,4,4)
• many modes: if two (or more) numbers share the max value, then there is more than one mode. 
• (1,2,3,3,3,4,5,6,6,6,7,8,9) -> two modes: 3, 6

Notation: 

• a common language used to communicate mathematical ideas. Think of notation as a universal language used by academic and industry professionals to convey mathematical ideas. (+, -, /…etc.)

Properties of Notation

• Understanding how to correctly use notation makes you see really smart.
• It allows you to read the documentation, and implement an idea to your own problem.
• It makes ideas that are hard to say in words easier to convey.

Cited from Digital Foundations Nanodegree, Udacity