Data Intelligence, Business Analytics
Salary mostly depends on experience, education, location, industry, and unfortunately, factors such as gender. Also, most data scientists have all the three skills and more (R + Python + SQL), so it is hard to assess which one is the most valuable.
Source for picture: click here (numbers are from 2014)
You could do a survey, asking data scientists which skills they were hired for, and break the results down into 8 categories:
And then compute the average salary in each category, maybe broken down by education / experience / location. Or you can think logically, concluding that
Then you can do some search using Indeed.com, and get salary per location for these three skills. Below are numbers for San Francisco, as of April 2016 (big contrast with the above picture corresponding to 2014, but the numbers below are for all job ads including architects and software engineers, not just data scientists). The number in parentheses represents the number of job openings.
It seems, if this data is correct, that SQL commands higher salaries than R, contrarily to my intuition. These numbers, based on recent job ads, can be found here (you can select the skill or location). Do you know why SQL commands higher earnings than R?
Other interesting search results for San Francisco include the following:
Python + R
Python + SQL
R + SQL
Sounds like Python + SQL might be the best combination. What is weird is that Python + R seems to command a lower salary than just Python alone. And if you know SQL, it gives you a nice boost if you are an R programmer.