Chapter 9

1. The original two testers, B and Z, were progressing at a steady rate which was not quite enough to keep up with the goal. Tester D was added in January but the team's total output was not improved. This could be due to effort diverted from testing to provide support to D or to verify his tests were done properly. On January 8, C and K were thrown into the mix while B took a day off. We can presume C and K knew what they were doing as the group output went up and they almost caught up with the goal line. K and Z did not participate after that and the output went back down even as B returned. Ultimately only D was left on the project as presumably the others were reassigned to more vital testing. D completed seven tests on the 12 ^th but it remains to be seen if he can sustain this output and hold the fort until this project can get its testing staff back up to where it should be. The two important observations here are that you can't treat every tester as an identical plug-in replacement for any other tester ‚ they each have their own strengths and skill sets ‚ and adding more testers does not guarantee a proportional increase in team output, especially during the first few days.

2. Test execution is currently 22 tests behind the goal. In ten working days, the team needs to complete 10 * 12 tests to match the planned rate, plus the 22 tests needed to catch up. This means 142 tests in ten days. Strictly going by the average rate of about four tests per day provided in Figure 9.3, three testers would only complete 120 tests in that time, but four testers could complete 160 (4 testers * 4 tests/day * 10 days). There is currently one tester, so three more need to be added. In a situation like this, it's good to staff a little above what's needed to account for startup and learning curve time. The extra 18 staff days between the need (142) and the projection (160) will come in handy.

3. Tester C made the best use of her test opportunity to find the most defects per test. However, other testers such as B and Z were able to perform many more tests and find a few more defects. Since "Best Tester" is based on the combined overall contribution to tests completed and defects found, C is not in the running. It's still important to identify C's achievements and recognize them. If B and Z could have been as "effective" as C, they could have found about six more defects each; a very significant amount.

4. Tester's X 130 tests puts the total tests run for the project at 700. Since Z is the current title holder, X has to have better numbers than Z. Z's new test contribution is 169/700 = 24%. X's test contribution is 130/700 = 18.5%. X needs to contribute 7% more of the defects found than Z. Let "x" be the number of defects X needs to find. Prior to X's defects, the defect total is 34. When X's defects are found, the new defect total will be 34 + x. X's defect contribution will be x / (34 + x) and Z's contribution is 9 / (34 + x). Since X's contribution must be 7% (0.07) higher than Z's, the equation to solve is x / (34 + x) = (9 / (34 + x)) + 0.07. Eliminate the fractions by multiplying the equation by (34 + x). This gives you x = 9 + (34 * 0.07) + (x * 0.07). Subtract 0.07x from both sides of the equation and add the constants remaining on the right side to get 0.93x = 11.38. Divide by 0.93 to solve for x, which is 12.23. Since you can only have whole numbers of defects, X needs to find 13 defects to grab the "Best Tester" crown.

5. Some positive aspects of measuring participation and effectiveness: some people will do better if they know they are being "watched," some people will use their own data as motivation to improve on their numbers during the course of the project, provides a measurable basis for selecting "elite" testers for promotion or special projects (as opposed to favoritism for example), testers seeking better numbers may interact more with developers to find out where to look for defects.

   Some negative aspects: effort is required to collect and report this tester data, it can be used as a "stick" against certain testers, may unjustly lower the perceived "value" of testers who make important contributions in other ways such as mentoring, could lead to jealousy if one person constantly wins, testers may argue over who gets credit for certain defects (hinders collaboration and cooperation), some testers will figure a way to exceed at their individual numbers without really improving the overall test capabilities of the team (such as choosing easy tests to run).