Jackknife and linear regression in Excel: implementation and comparison

The comparison is performed on a data set where linear regression works well: salary offered to a candidate, based on programming language requirements in the job ad: Python, R or SQL. This is a follow-up to the article highest paying programming skills. The increased accuracy of linear regression estimates is negligible, and well below the noise level present in the data set. The Jackknife method has the advantage to be more stable, easy to code, easy to understand (no need to know matrix algebra), and easy to interpret (meaningful coefficients). Jackknife is not the first regression approximation developed by the author: check my book pages 172-176 for other examples.