Important Statistics Terms

• Prevalence: Prevalence is the fraction of people in a population who have a disease/condition/characteristic at a point in time.
  
  
• Rate: A calculation describing the speed at which new disease or health events occur. For example, the rate of asthma death in Michigan is 12.6 per million people per year.
  
  
• Work-Related Asthma: Work-related asthma is asthma caused by exposures at work. It can also be existing asthma made worse by exposures at work.
  
  
• Asthma Emergency Department Visit: An asthma emergency department visit is one where asthma is the primary reason for the visit. (International Classification of Disease (ICD) Version 9 Clinical Modification code 493.XX)
  
  
• Asthma Hospitalization: An asthma hospitalization is one where asthma is the primary reason for the hospital stay. (International Classification of Disease (ICD) Version 9 Clinical Modification code 493.XX)
  
  
• Asthma Death: An asthma death is one where asthma is the primary reason for the death. (International Classification of Disease (ICD) Version 9 Clinical Modification code 493.XX or Version 10 codes J45 and J46)
  
  
• Persistent asthma (HEDIS^®): Persistent asthma is defined according to the Health Plan and Employer Data and Information Set (HEDIS^®) definition from the National Committee for Quality Assurance (NCQA). The criteria for this definition are:
• at least four occasions where asthma medicine is given out OR
• at least one visit to an emergency room where the primary reason was asthma OR
• at least one visit to the hospital where the primary reason was asthma OR
• at least four visits to a doctor where the primary reason was asthma and at least two occasions where asthma medicine is given out.
  
  
• Statistically Significant Result: A result is called statistically significant if it is unlikely to have occurred by chance. "A statistically significant difference" simply means there is statistical evidence that there is a difference; it does not mean the difference is necessarily large, important, or significant in the common meaning of the word.