Productivity is a relative measure, and must be compared to something else meaningful to be effective. What are the three ways of measuring productivity

past performance, overall goal, other's performance.

Explanation:

Productivity can be measured to three main things, past performance, overall goal, others performance. Each of these are effective and meaninful factors to compare productivity to. They allow you to determine if productivity is increasing, decreasing, or if it could be better. If other individuals perfomance is better than yours and they are similar to you in every other factor then that means that your productivity can and should be better than what it currently is. Therefore, each one of these comparisons provide useful and valuable data.

answer; /// the above statement is (true);

the first successful, urban blues recording, selling more than 75,000 copies, was made in year 1920.

mamie smith recorded the first commercially successful example of the urban blues,   with the recording of “crazy blues”."crazy blues" was recorded on august 10, 1920, in new york city. within a month of the release of “crazy blues” it had sold 75,000 copies.