11. Nine Percent of Men and One-Half Percent of Women Are Color-Blind

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• Most people who are color-blind aren't blind to all colors. Most just have a color deficiency. 

• Men are more likely to be color-blind because most of the color genes are on the X chromosome. Men only have one while women have two. 

• There are different kinds of color blindness but the most common is called "red-green" which is a difficulty in distinguishing reds, yellows, and greens. 

• There are ways you can make your site more friendly to people who are colorblind:  1. If you are using color to give specific meaning you need a redundant coding scheme like using color and line thickness, so people won't need to see specific colors to decipher the code.  2. You can also pick a color scheme that works for all the types of color blindness. This way the colors look the same regardless if they are color-blind. 

• Example Color Wheels (binary/octet-stream)

• http://cruxcollaborative.com/insights/understanding-color-blindness-guide-to-accessible-design