4. The authors suggest a SI score of s5.0 as the cutpoint between "safe" (-) and "hazardous" (+). Based on this, and using the data in Table 4: (a) construct a contingency table, (b) verify the sensitivity, and specificity, and (c) determine the positive predictive value and negative predictive value for the SI cutpoint. 5. A company with 275 workers would like to apply the Strain Index. The company can lower all its jobs to an SI score of 13.5 or less. a. Construct a contingency table based on Table 4 and a SI cutpoint of s 13.5 b. Determine the sensitivity, specificity, PPV, and NPV, based on (a) c. In your opinion, are the numbers from (b) acceptable? Why or why not? d. Using the incident rates from Table 4, and the data from the Table below, how many injuries can the company expect among its 275 employees during the next year, if all jobs are reduced to a score of 13.5 or less? State all your assumptions. e. Using the same assumptions, how many injuries could the company expect if they reduce the job scores to s 5? Table: Summary of Current SI Measured Exposures for N=275 workers Current SI Score Number of Range (SI) Workers (N) SI S 5.0 17 5.0 13.5 136 Very slow SI Score 54 13.5 7 81 54 29 20 10 13.5 36 very fast Wory slow 4-0 TABLE IV. Incidence Rates and Exposure Data for the Preliminary Assessment, with Numerical Data for the Quantitative Task Variables and Assigned Ratings for the Qualitative Task Variables Duration Efforts Hand Speed Job Intensity of of per No. of FTER Inc Wrist Duration Exertion Exertion Minute Posture Exertion per Day 1 210 hard 100% very good vary slow 4-8 2 3 160 hard 15% 4-8 3 4 very slow 135 somewhat hard 10 4-8 4 6 130 somewhat had 100N 10 5 24 78 somewhat had 39% 20 bad 4 75 near maximal Vory slow 4-8 7 1 60 very hard 8 8 53 near maxima very good 9 2 30 very fast hard 42% very good very slow 4-8 10 6 30 light 85% bad very fast 11 2 30 somewhat hard very good 4-8 12 12 25 near maximal 5 very slow 13 1 0 light very good 14 3 0 light 6396 7 very good very slow 15 6 light 11% 8 very good very slow 16 1 0 light 28% very slow 17 1 0 light 40% very good very silow 60, and CTS represented 38% of the morbidity. At this time, this increased percentage of CTS is considered secondary to small numbers rather than some correlation with an Sl score > 60. The relationship between SI score and mean incidence rate is shown in Figure 1. There was an increase in mean incidence rate for upper extremity disorders with an increase in SI score To examine the effects of observer rating variation, a sensitivity analysis was conducted by promoting and demoting an individ- ual task variable by one rating for all jobs, then counting the number of jobs that cross the tentative Sl score threshold of 5. WY Med TABLE V. Analysis of Morbidity by SI Score Range SI Number of Conditions Score 3 Jobs FTE Elbow Hand Wrist CTS 5 14 30 0 0 5-30 7 34 9 21 7 31-60 3 34 12 30 6 >>60 1 6 3 5 Al handwrist morbidity CTS FIGURE 1. Meer incidence rose versus score AM WD HYO ASOC/May 452 4. The authors suggest a SI score of s5.0 as the cutpoint between "safe" (-) and "hazardous" (+). Based on this, and using the data in Table 4: (a) construct a contingency table, (b) verify the sensitivity, and specificity, and (c) determine the positive predictive value and negative predictive value for the SI cutpoint. 5. A company with 275 workers would like to apply the Strain Index. The company can lower all its jobs to an SI score of 13.5 or less. a. Construct a contingency table based on Table 4 and a SI cutpoint of s 13.5 b. Determine the sensitivity, specificity, PPV, and NPV, based on (a) c. In your opinion, are the numbers from (b) acceptable? Why or why not? d. Using the incident rates from Table 4, and the data from the Table below, how many injuries can the company expect among its 275 employees during the next year, if all jobs are reduced to a score of 13.5 or less? State all your assumptions. e. Using the same assumptions, how many injuries could the company expect if they reduce the job scores to s 5? Table: Summary of Current SI Measured Exposures for N=275 workers Current SI Score Number of Range (SI) Workers (N) SI S 5.0 17 5.0 13.5 136 Very slow SI Score 54 13.5 7 81 54 29 20 10 13.5 36 very fast Wory slow 4-0 TABLE IV. Incidence Rates and Exposure Data for the Preliminary Assessment, with Numerical Data for the Quantitative Task Variables and Assigned Ratings for the Qualitative Task Variables Duration Efforts Hand Speed Job Intensity of of per No. of FTER Inc Wrist Duration Exertion Exertion Minute Posture Exertion per Day 1 210 hard 100% very good vary slow 4-8 2 3 160 hard 15% 4-8 3 4 very slow 135 somewhat hard 10 4-8 4 6 130 somewhat had 100N 10 5 24 78 somewhat had 39% 20 bad 4 75 near maximal Vory slow 4-8 7 1 60 very hard 8 8 53 near maxima very good 9 2 30 very fast hard 42% very good very slow 4-8 10 6 30 light 85% bad very fast 11 2 30 somewhat hard very good 4-8 12 12 25 near maximal 5 very slow 13 1 0 light very good 14 3 0 light 6396 7 very good very slow 15 6 light 11% 8 very good very slow 16 1 0 light 28% very slow 17 1 0 light 40% very good very silow 60, and CTS represented 38% of the morbidity. At this time, this increased percentage of CTS is considered secondary to small numbers rather than some correlation with an Sl score > 60. The relationship between SI score and mean incidence rate is shown in Figure 1. There was an increase in mean incidence rate for upper extremity disorders with an increase in SI score To examine the effects of observer rating variation, a sensitivity analysis was conducted by promoting and demoting an individ- ual task variable by one rating for all jobs, then counting the number of jobs that cross the tentative Sl score threshold of 5. WY Med TABLE V. Analysis of Morbidity by SI Score Range SI Number of Conditions Score 3 Jobs FTE Elbow Hand Wrist CTS 5 14 30 0 0 5-30 7 34 9 21 7 31-60 3 34 12 30 6 >>60 1 6 3 5 Al handwrist morbidity CTS FIGURE 1. Meer incidence rose versus score AM WD HYO ASOC/May 452