A calculation - not an opinion
The first documented index, the Dow Jones Transportation Average, was created in 1884 by Charles Dow and Edward Davis Jones. They created the “Customer’s Afternoon Letter,” a precursor to the Wall Street Journal, to provide unbiased reporting. It included a simple market average, based on 11 companies primarily from the railway sector, to help readers understand if the overall market was advancing or retreating.
Since then, the construction of indexes has evolved greatly, but basic principles of impartiality and transparency remain relevant today.