West Virginia Bureau for Public Health
350 Capitol Street • Room 206 • Charleston, WV 25301-3715
Phone: (304) 558-0644 Fax: (304) 558-1553

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Glossary of Terms

Glossary of Terms
BMI – Body Mass Index, used to define overweight and obesity
Adult BMI – For adults, overweight and obesity ranges are determined by using weight and  
height to calculate a number called the “body mass index” (BMI). BMI is used because, for most
people, it correlates with their amount of body fat.

BMI = (
            Weight in Pounds             
(Height in inches) x (Height in inches)
) x 703

To calculate BMI, the following  
formula is used.
 

(
            220 lbs.            
(75 inches) x (75 inches)
) x 703 = 27.5

For example, a person who weighs 220 pounds and is 6 feet 3 inches tall has a BMI of 27.5.

Category
BMI range
Underweight
Less than 18.5
Normal
18.5 to 24.9
Overweight
25.0 to 29.9
Obese
30.0 or greater

Body Mass Index numbers are categorized as follows:

  

 

It is important to remember that although BMI correlates with the amount of body fat, BMI does not directly measure body fat. As a result, some people, such as athletes, may have a BMI that identifies them as overweight even though they do not have excess body fat. Other methods of estimating body fat and body fat distribution include measurements of skinfold thickness and waist circumference, calculation of waist-to-hip circumference ratios, and techniques such as ultrasound, computed tomography, and magnetic resonance imaging (MRI).

 
  
BMI for Children and Teens
For children and teens, BMI ranges above a normal weight have different labels (at risk of overweight and overweight). These BMI ranges correspond to the adult BMI ranges of
overweight and obese, respectively. Additionally, BMI ranges for children and teens are defined
so that they take into account normal differences in body fat between boys and girls and
differences in body fat at various ages. BMI for children, also referred to as BMI-for-age, is 
gender and age specific. BMI-for-age is plotted on gender specific growth charts.

 

Each of the CDC BMI-for-age gender specific charts contains a series of curved lines indicating specific percentiles. Healthcare professionals use the following established percentile cutoff points to identify underweight and overweight in children.

Category
BMI range
Underweight
BMI-for-age < 5th percentile 
Normal
BMI-for-age 5th percentile to < 85th percentile
At risk of overweight
BMI-for-age 85th percentile to < 95th percentile
Overweight
BMI-for-age > 95th percentile

 
 
 
 
 
 
 
 
BRFSS – Behavioral Risk Factor Surveillance System – an annual random-sample telephone survey of adult West Virginians regarding their health status and the behaviors that impact health. All U.S. States and some territories participate in BRFSS. The BRFSS is sponsored by the Centers for Disease Control. http://www.cdc.gov.brfss
 
Confidence Interval – Instead of a single estimate for the mean, a confidence interval generates a lower and upper limit for the mean. The interval estimate gives an indication of how much uncertainty there is in the estimate of the true mean. The narrower the interval, the more precise is the estimate.
 
Evaluation – A process that attempts to determine as systematically and objectively as possible the relevance, effectiveness and impact of activities in light of their objectives.
 
Incidence – A measure of the frequency with which an event, such as a new case of illness, occurs in a population over a period of time. The denominator is the population at risk, the numerator is the number of new cases occurring during a given time period.
 
Mean – commonly called the average, it is calculated by adding together all the individual values in a group of measurements and dividing by the number of values in the group.
 
Median – the measure of location which divides a set of data into two equal parts
 
Mode – the most frequent occurring value in a set of observations
 
Morbidity – any departure, subjective or objective, from a state of physiological or psychological well-being.

PedNSS – Pediatric Nutrition Surveillance System – A 100% sample of a convenience population, this system contains measured heights and weights, and breastfeeding status of low-income infants and toddlers (up to age 5) who participate in the WV WIC Program. Some dietary information and TV viewing habits will be forthcoming. 

PNSS - Pregnancy Nutrition Surveillance System – A 100% sample of a convenience population, this system contains measured heights and weights of low-income pregnant and post-partum West Virginia women who participate in the WV WIC Program. 

PRAMS – Pregnancy Risk Assessment Monitoring System – Maternal and Child Health population-based mail and telephone survey of recently post-partum mothers, this system contains self-reported pre-pregnant height and weight of mother and breastfeeding information. http://www.cdc.gov/prams/index.htm
 
Percentile – the set of numbers from 1 to 100 that divide a distribution into 100 equal parts, with each interval containing 1/100th of the observations. A particular percentile, say the 5th percentile, is a cut point with 5% of the observations below it, and the remaining 95% of the observations above it.
 
Prevalence – The proportion of people in population who have a particular disease or attribute at a specified point in time or over a specified period of time.
 
Range - in statistics, the difference between the largest and smallest values in the distribution.
 
Rate – an expression of the frequency with which an event occurs in a defined population
 
Self-reported [BMI] – an individual simply states their height and weight, as opposed to having height and weight measured by a trained technician. 
 
Sentinel Surveillance – a surveillance system in which a pre-arranged sample of reporting sources agrees to report all cases of one or more conditions.
Significance In normal English, "significant" means important, while in Statistics "significant" means probably true (not due to chance). A research finding may be true without being important. When statisticians say a result is "significant" they mean it is very probably true. They do not (necessarily) mean it is highly important.
Years of Potential Life Lost – A measure of the impact of premature mortality on a population, calculated as the sum of the differences between some predetermined minimum or desired life span the age of death for individuals who dies earlier than that predetermined age.
 
YRBSS – Youth Risk Behavior Surveillance System – a written survey of teen health status and health behaviors administered to 9th through 12th grade students in West Virginia every other year. 49 U.S. States and territories participate in YRBSS. The YRBSS is sponsored by the Centers for Disease Control. http://www.cdc.gov/HealthyYouth/yrbs/index.htm
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