Because some Muslims are new immigrants and others are recent converts, reliable estimates are difficult.
A report released this week by the General Accounting Office, an investigative branch of Congress, said such estimates were difficult to confirm.
Global estimates are difficult because there is no uniform way to include antimicrobial resistance in causes of death.
Because they are solitary and hard to spot, population estimates are difficult, though the foundation believes there are fewer than 30,000 in the country.
However, methodologies for the estimation of tree root biomass are varied and their effectiveness in terms of the precision of biomass and carbon estimates is difficult to evaluate.
Although AGB is an important variable for evaluating ecosystem function and structure across the landscape, such estimates are difficult to generate without high-resolution satellite data.
Franklin Thomas, chairman of the Sept. 11 Fund, said that although estimates are difficult, his instinct told him that no more than 25percentt of the fund's remaining $251.4 million would be paid out as cash grants to individual families and victims.
However, the application of these methods to forest trees is difficult, because the creation of appropriate genetic material is extremely time-consuming in long-lived, woody plants, and life-time fitness estimates are difficult or impossible to obtain.
Several art experts and dealers said that a major Deas work would easily go for millions of dollars at auction — though estimates are difficult because it has happened so rarely.
While those estimates are difficult to verify, the nation's economy since April has added an average of only about 40,000 jobs a month, raising concerns about a double-dip recession.
