Hi hope all is well the textbook is the 7th edition for Biostatistics

A nine-laboratory cooperative study was performed to evaluate quality control for susceptibility tests with 30-g netilmicin disks [6]. Each laboratory tested three standard control strains on a different lot of Mueller-Hinton agar, with 150 tests performed per laboratory. For protocol control, each laboratory also performed 15 additional tests on each of the control strains using the same lot of Mueller-Hinton agar across laboratories.

The mean zone diameters for each of the nine laboratories are given in Table 6.9.

*6.20

Provide a point and interval estimate (95% CI) for the interlaboratory standard deviation of mean zone diameters for each type of control strain, if each laboratory uses different media to perform the susceptibility tests.

*6.21

Answer Problem 6.20 if each laboratory uses a common medium to perform the susceptibility tests.

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