Marcellus Shale - 17 of 16
Marcellus Shale FAQs - 16 Found
The USGS uses a statistically based process to calculate the likely range of its estimate. The USGS publishes a range of values that encompasses 90% of likely outcomes from its modeling process. That range extends from a 5% or greater likelihood of occurrence (the F5 value, or largest estimated value) to less than 95% likelihood of occurrence (the F95 value, or smallest estimated value). The F50 value is that model result value that occurs when 50% of the results are greater and 50% are lesser than the model results. We also calculate a mean or average value, which is the number commonly reported in the USGS press releases announcing an oil and gas resource assessment. Because the distribution of potential outcomes is not symmetrical, or evenly spread around the middle or most likely value, the mean is close to, but not identical to the F50 value.