The precise size of this effect is difficult to ascertain, as the causal relationships between oil prices and the dollar are complex and run in both directions.
However, the price of oil has risen significantly in terms of all major currencies, suggesting that factors other than the dollar, notably shifts in the underlying global demand for and supply of oil, have been the principal drivers of the increase in prices. Another concern that has been raised is that financial speculation has added markedly to upward pressures on oil prices.