2. Chapter 2-Safety Analysis A Statistical Approach

3. Chapter 2-Safety Analysis: A Statistical Approach2 Roles of Statistics in Safety Although the myth is that Statistics are too hard for a regular person to understand, it is accutually quite the opposite. Statistics are relatively easy to understand. Statistical data serves a number of functions in safety.

4. Chapter 2-Safety Analysis: A Statistical Approach3 Statistics in Safety Data is frequently used to determine problem areas. Statistics can also be helpful in developing strategies in safety education.

5. Chapter 2-Safety Analysis: A Statistical Approach4 Statistics defined Statistics has to do with the extraction of information from numerical data. There are two types of Statistics: 1. Descriptive Statistics 2. Inferential Statistics

6. Chapter 2-Safety Analysis: A Statistical Approach5 Two Types of Statistics Descriptive Statistics Give information about the characteristics of a particular group. Example: Total deaths for motor vehicle accidents. Inferential Statistics Consists of estimations, generalizations, or predictions about a particular group. Example: A prediction of how many people will be traveling this year on Thanksgiving.

7. Chapter 2-Safety Analysis: A Statistical Approach6 Presentation of Data Frequency Distributions can make large numbers of scores easier to work with. It presents the numbers in an efficient manner.  Any set of Values are known as a distribution.

8. Chapter 2-Safety Analysis: A Statistical Approach7 Percentage as a Presentation of Data Percentages are another form of presenting data.  They are derived by dividing the number of cases in interest by the total number of cases. % of Deaths=Number of deaths in age group Number of Total deaths

9. Chapter 2-Safety Analysis: A Statistical Approach8 Presentation of Data Rates are percentages based on particular population. Unlike percentage, rates control for population;rates are always based on the same figure;usually 100,000. The specific death rate is the number of deaths that occur each year for every 100,00 persons in a certain population.

10. Chapter 2-Safety Analysis: A Statistical Approach9 Death Rate A death rate would be found by using this equation: Specific Death Rate= Number of deaths for a particular population X’s100,000 Specific Population

11. Chapter 2-Safety Analysis: A Statistical Approach10 Presentation of Data Graphical Presentations enable the reader to take in information based on pictures or graphics. A graph can enable one to see the “big picture” but not the raw data.

12. Chapter 2-Safety Analysis: A Statistical Approach11 Errors and Problems The collection of accurate data is vital in the field of safety. There are two important aspects of data collection 1. Validity- How close does the data correspond to the situation? 2. Reliability- How closely do the observations match each other?

13. Chapter 2-Safety Analysis: A Statistical Approach12 Finding Reliable Sources The National Safety Council is one of the most reliable sources for nationwide data pertaining to accidents of all kinds. It was established in 1913, by an Act of Congress, and has now become a non- profit, nongovernmental organization that has become the leader in safety services.

14. Chapter 2-Safety Analysis: A Statistical Approach13 Finding Reliable Sources National Center for Health Statistics National Injury Information Clearinghouse National Criminal Justice Reference Service(NCJRS) National Highway Traffic Safety Administration(NHTSA)

15. Chapter 2-Safety Analysis: A Statistical Approach14 National Highway Traffic Safety Administration Since 1975, NHTSA has analyzed fatal motor vehicle crashes, which is known as Fatal Accident Reporting System(FARS). With this information, researchers have been able to come up with information that is valuable in determining the causes for a crash.

16. Chapter 2-Safety Analysis: A Statistical Approach15 The Key to Accurate Statistics Valid and Reliable Safety Statistics depend on the individuals who provide the safety services. Writing the facts down accurately may be time consuming, but it is helpful in Statistical Data.

17. Chapter 2-Safety Analysis: A Statistical Approach16 Classification of Accidents Most Safety Researchers classify accidents in four basic groups: 1. Motor Vehicle Accidents 2. Work-related Accidents 3. Home Accidents 4. Public Accidents Then the information is broken down further within the groups.

18. Chapter 2-Safety Analysis: A Statistical Approach17 Changes in the Accident Scene 1903-1989 Since 1903, The accident death rate has declined by 56%. Since 1979, the accident death rate has dropped 10%. 1903 1989 56%

19. Chapter 2-Safety Analysis: A Statistical Approach18 Modern Approaches to Accident Investigation First, the four factors that involve safety during an activity as discussed in chapter one: 1. Understanding the Difficulty 2. The Ability of the Performer 3. Immediate Sate of the Performer 4. Conditions of the Environment These four components make up a system

20. Chapter 2-Safety Analysis: A Statistical Approach19 Modern Approaches to Accident Investigation Accidents can be thought of as malfunctions in a system. An example would be the aerospace industry. Because of the highly sophisticated equipment, the engineers had to come up with systems safety analysis. They used this to predict when problems would occur so that they could be fixed before it happened. Now they are used in all industries.

21. Chapter 2-Safety Analysis: A Statistical Approach20 Modern Approaches to Accident Investigation Failure Mode and Effect Analysis- Each component or factor is evaluated on how it will affect the overall system if it fails. This is used to come up with plans for back-up components. Fault-Tree Analysis- Accident prevention model that reasons backwards from an event that is unwanted. It tracks the sequence of events leading up to this possible situation.

22. Chapter 2-Safety Analysis: A Statistical Approach21 Modern Approaches to Accident Investigation Management Oversight and Risk Tree (MORT)- Identifies the causes for an accident and evaluates the systems and how it may have contributed to the failure. Cost Benefits Analysis- Not accutually a method of investigation, but helps to determine when safety items are benefiting the situation on a cost based level.

23. Chapter 2-Safety Analysis: A Statistical Approach22 Modern Approaches to Accident Investigation Hazard Analysis- The identification of hazards before an accident occurs. Assesses the degree of risk. W.T. Fine developed a formula for evaluation the risk in a situation: R=C x E x P Risk Score=R Potential Consequences=C Exposure=E Probability of occurrence=P

24. Chapter 2-Safety Analysis: A Statistical Approach23 Modern Approaches to Accident Investigation Computer Profiles- A computer generate sentence made up of several injury factors strung together in a format that uses connecting phrases that make the sentence intelligible and show a relationship between the factors. The computer can then take many of these sentences and come up with a “trend” in the data. This can help in analyzing accidents of a certain nature.

25. Chapter 2-Safety Analysis: A Statistical Approach24 When System Safety Breaks Down Sometimes a minor oversight can cause a great disaster, such as the tragic Challenger explosion in 1986. This is why the safety analysis's are so important for prevention of accidents.

26. Chapter 2-Safety Analysis: A Statistical Approach25 Summary Statistical data is used to determine problem areas, and ultimately prevent accidents all together. Validity and Reliability are two factors that need to be taken into consideration when evaluating material-especially statistics. There are many systems in place to help prevent accidents from happening.

27. Chapter 2-Safety Analysis: A Statistical Approach26 Specific Death Rate = # of Deaths x 100,000 Specific Population Foundry 4x 100,000 500 = 800 Mining 9x 100,000 1000 = 900 Lumber 14x 100,000 2000 = 700 Construction 18 x 100,000 3000 = 600