was also discovered that, in general, 80% of a piece of software can be written in 20% of the total allocated time. Conversely, the hardest 20% of the code takes 80% of the time. This factor is usually a part of COCOMO estimating for software coding. Occupational health and safety Occupational health and safety professionals use the Pareto principle to underline the importance of hazard prioritization. Assuming 20% of the hazards account for 80% of the injuries, and by categorizing hazards, safety professionals can target those 20% of the hazards that cause 80% of the injuries or accidents. Alternatively, if hazards are addressed in random order, a safety professional is more likely to fix one of the 80% of hazards that account only for some fraction of the remaining 20% of injuries. Aside from ensuring efficient accident prevention practices, the Pareto principle also ensures hazards are addressed in an economical order, because the technique ensures the utilized resources are best used to prevent the most accidents. Other applications Engineering and quality control The Pareto principle is sometimes used in quality control where it was first created. It is the basis for the Pareto chart, one of the key tools used in total quality control and Six Sigma techniques. The Pareto principle serves as a baseline for ABC-analysis and XYZ-analysis, widely used in logistics and procurement for the purpose of optimizing stock of goods, as well as costs of keeping and replenishing that stock. In engineering control theory, such as for electromechanical energy converters, the 80/20 principle applies to optimization efforts. In the systems science discipline, Joshua M. Epstein and Robert Axtell created an agent-based simulation model called Sugarscape, from a decentralized modeling approach, based on individual behavior rules defined for each agent in the economy. Wealth distribution and Pareto's 80/20 principle emerged in their results, which suggests the principle is a collective consequence of these individual rules. Health and social outcomes In 2009, the Agency for Healthcare Research and Quality said 20 percent patients incurred 80 percent of health-care expenses due to chronic conditions. A 2021 analysis showed unequal distribution of healthcare costs, with older patients and those with poorer health incurring more costs. A New Zealand Dunedin Study that by the age of 38, 22% of children in the study accounted for 81% of criminal convictions, 78% of pharmaceutical prescriptions, and 66% of welfare benefits within the group. This