Problem with installing any app via NPM What's going wrong?

I try to install something and after the install I can launch it. System doesn't see the installed app.

For example:
I tried to install "appium-doctor" and I did it successfully.

npm install -g appium-doctor
/Users/oleg/.npm-global/bin/appium-doctor -&gt; /Users/oleg/.npm-global/lib/node_modules/appium-doctor/appium-doctor.js
/Users/oleg/.npm-global/lib
└── appium-doctor@1.4.1 


After that I tried to launch the appium-doctor, and I got the error:

iMac-Ponomarenko:~ oleg$ appium-doctor
-bash: appium-doctor: command not found


My environment:
 - npm -v prints: 4.1.2 
 - node -v prints: v6.9.5
 - npm config get registry prints: https://registry.npmjs.org/
 - OS: OS X El Capitan

What problem is the feature intended to solve?

I want to install appium 1.6.3. And i need "gulp" for it.
Try it by providing full path, like /Applications/some_folder/appium-doctor to launch this app. It looks like system is not able to locate the binary 'appium-doctor'.
If it works then you can add that $path in .bash_profile.