Statistics frequency rate

One approach is to compare the risks, calculated from a hazard analysis, with risks that are generally considered acceptable such as, the average risks in the particular industry, and the kind of risks that people accept voluntarily. One measure of the risk to life is the Fatal Accident Frequency Rate (FAFR), defined as the number of deaths per 108 working hours. This is equivalent to the number of deaths in a group of 1000 men over their working lives. The FAFR can be calculated from statistical data for various industries and activities some of the published values are shown in Tables 9.8 and 9.9. Table 9.8 shows the relative position of the chemical industry compared with other industries Table 9.9 gives values for some of the risks that people accept voluntarily. 

According to the Bureau of Labor Statistics, the injury frequency rate for all manufacturing companies rose from 11.8 in 1960 to 15.3 in 1970. The National Safety Council estimates that there are around 15,000 job-related deaths each year and another 2,300,000 workers suffer disabling injuries. The total cost associated with these accidents is nearly 9,500,000,000/yr. 14 These figures are conservative,... 

Statistics do not tell the whole story. Not infrequently effects are seen at very low frequencies (not at statistically significant rates) that the toxicologist may think important and likely to be due to the chemical. The typical case involves the appearance of very rare or highly unusual diseases or forms of injury in treated animals - diseases or injuries that historically have never been observed, or observed only at extremely low frequencies, in untreated animals. 

Shannon et al. (1996) is an example of a study limited in both of these ways. It doesn t have any variables on employees involvement with the company s financial returns, and it doesn t present the results of the analysis in a multivariate ftamewoik. The researchers examine a matched sample of questionnaires sent to firms in Ontario with data on those firms lost-time frequency rates (equivalent to the analysis of claim frequency given below). Survey questionnaires include responses from both workers and management. The paper discusses only univariate statistical analyses that compare various workplace practices to whether a firm has a low, medium, or high claim frequency. A multivariate regression analysis is mentioned but not reported on in the paper. 

However, during recent years, a positive declining trend of accident frequency rates is visible in the statistics for the construction sector in Finland, thus indicating a positive safety development (see Fig. 1). 

Variations in monthly frequency rate In a particular year the statistical significance of variations in injury rates from month to month is assessed against the injury rate for the whole of the previous year. This annual injury frequency rate (IFR) is ... 

Dr. chapman McGrew, a colleague at Salisbury University, has verified that a chi-square table of these statistics indicates that there is a less than i percent chance that some factor other than the presence or lack of guardians influenced the success or failure of these orphans. Dr. McGrew cautioned, however, that one of the cells in the chi-square table had a low frequency rate. 

Accidents are relatively rare events and so frequency rates based on them may not be statistically vahd (an in-depth discussion on accident statistics is covered later in this chapter). 

First and foremost, management must clearly understand and appreciate what accident frequency rates are and how they should be used. This is done only by educating members of management on safety measurement techniques so they can understand the strengths and weaknesses of results, measurements, causes, and effects. Once they understand the potential and how to interpret and use aU three types of measurements, they wiU be more likely to employ a balanced and professional approach to using accident statistics. 

This is a very basic method for calculating upper and lower control limits. Other methods can also be used to calculate these hmits. To ensure that the statistical control charts are as reliable as practical, keep several guidelines in mind. First, use accident rates that have as many sets of data as possible. For example, an aU injury/iUness frequency rate works better than a lost time frequency rate. Second, try to use at least twenty sets of data in calculating the base rate or average. In our example we only used five data points for practical purposes. However, they represented 60 individual monthly frequency rates. 

Miner s safety performance recognition, circa 1920s 20 The systems model of health and safety management 24 The size of mobile mine equipment continues to increase 27 Simple model of outcomes dependent on culture and systems 32 Statistical control chart with incident rate variation 33 Universal Copper and Metals Mine accident frequency rate control chart 55... 

Meanwhile, international statistical comparisons mean little, as there are so many measuring tools and so many different criteria for measurement. There is no general agreement on how to calculate frequency rates, or on what counts as a reportable injury. Even in the UK, the rules change every 5 to 10 years, and invalidate previous data sets. And there is good evidence that many injuries go unreported. 

Much has been written about accountability, the last of the leadership best practices. In the safety area, what employees and team members are held accountable for matters greatly. Holding people accountable for incident frequency rates only makes sense if the numbers are statistically valid. More important, upstream activities that produce safety results should be measured and accountabilities established for them. 

Once a control chart is in use, new quality assessment data should be added at a rate sufficient to ensure that the system remains in statistical control. As with prescriptive approaches to quality assurance, when a quality assessment sample is found to be out of statistical control, all samples analyzed since the last successful verification of statistical control must be reanalyzed. The advantage of a performance-based approach to quality assurance is that a laboratory may use its experience, guided by control charts, to determine the frequency for collecting quality assessment samples. When the system is stable, quality assessment samples can be acquired less frequently. 

The field of statistics as a separate discipline began m the early to mid nineteenth century among German, British, French, and Belgian social reformers, refeired to as statists i.e., those that were concerned with numbers related to the state, including crime rates, income distributions, etc. [34] The appeal of frequency-based interpretation of probability would have been natural m the study of large human populations. 

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