Figure 6. Histogram of normalized core temperatures: did not pass normality test Figure 7. Normal probability plot of normalized core temperatures: did not pass normality test Because it is very useful to quantify the use of the precooking heating step for processing under HACCP, we have shown how this can be done by use of non-destructive testing of core temperatures of precooked fish. The advantage of being able to measure core temperatures quickly is that the precooker operators can wait and re-measure the core temperatures if the initial readings are too low to reach the minimum target, given that core temperatures continue to rise after the end of precooking. It is relatively simple to develop a computer spreadsheet that calculates the statistics relevant to 280 Food Protection Trends July/August the evaluation of the proposed CL using the data from a tally sheet if the factory management chooses to use the calculated average and standard deviation. Normality testing is a fundamental requirement of using a variable sampling plan. When the core temperatures are grouped in a frequency chart or tally sheet, a histogram is naturally formed, and that histogram can be inspected by floor personnel for normality or near-normality. The histogram is effective only for moderate to large sample sizes (n > = 50) (7). For smaller sample sizes (n < 50), grouped