My mother is a math professor, so I speak in numbers. There is an important difference between the median and the average, even though the two terms are often used interchangeably. In today’s statistics lesson, I will define the two terms and illustrate the difference with some San Francisco real estate market statistics. It will be a quick and painless math lesson, I promise. Bear with me. :-)

**median** – To find the median value, all the numbers in the sample are placed in order of value and the number in the middle is the median. The easiest way to remember “median” is to simply call it “the middle number”. The number 3 is the median number in the following sample:

1

1.5

2

2.5

**3**

3.5

4

4.5

19

When the sample is listed in ascending value, you’ll see the number 3 has four numbers before it and four numbers after it. It’s the one in the middle, aka the median.

**average** - The average is the number that most accurately represents a data set (also known as the “mean”). To find the average value of a set of numbers, the numbers are first added together, then divided by the total number of inputs. Take the same sample used above:

1

1.5

2

2.5

3

3.5

4

4.5

19

**median**is 3 and the

**average**is 4.56.

*usually*the most accurate representation of a set of numbers, like with home prices. Averages are misleading because they include the outliers–the very large and the very small numbers that skew the results. The average price per square foot in San Francisco is a much different number than the median price per square foot in San Francisco. While they both follow the same trajectory over time, the difference appears because some high-priced properties skew the average. The chart below shows the past few years of median price per square foot and average price per square foot in San Francisco. (red line is median price, yellow-greenish line is average price)