# Statistics and Difference

Introduction:

The report analyses the result of a study on workers from brick and tile industries conducted by the Health and Safety Laboratory (HSL). HSL put down few criteria’s to the workers which being that neither of the workers from the tiles and brick industries should have worked in both the industries and that they did not smoke. The criteria’s put across was an assurance to attain reliable results.

The essence of the study lies in detecting any difference in the health of the workers in these industries (as identified by cell damage) if any and also to determine if any relationship exists between the length of service and the recorded health effect.

The Null Hypothesis (Ho) states that no

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MANN WHITNEY TEST Results & CI Of Tile & Brick Manufacturing Operations

Table 2:illuminates the number of samples used in the Mann Whitney test and the obtained median for data of brick and tile manufacturing operations

Sample type | Number of sample | Median | Tile | 27 | 1.100 | Brick | 38 | 1.370 |

Point estimate for ETA1-ETA2 is 0.200

95.0% CI for ETA1-ETA2 is (-0.323, 0.800)

W = 1319.0

Test of ETA1 = ETA2 vs. ETA1 not = ETA2 is significant at 0.3905

The test is significant at 0.3903 (adjusted for ties).

The results shows a confidence interval of 95% between 0.323 and 0.800 in the %damaged cells of workers In the brick and tile operations. Contrariwise the difference in the median is 0.200(estimated), which means that 0.200%(approximately) more % of damaged cells in workers of the brick operations than those of the tile operations. A 100% certain analysis cannot be proven as the confidence interval (CI) is only 95%, hence creating a need for more data in order to achieve a 100% certain analysis.