National security, unlocked. Each Thursday, host Mary Louise Kelly and a team of NPR correspondents discuss the biggest national security news of the week. With decades of reporting from battlefields ...

This widely used method of calculating returns considers a portfolio's cash flows Will Kenton is an expert on the economy and investing laws and regulations. He previously held senior editorial roles ...

Computational models are mathematical models used to numerically study the behaviour of complex systems by means of a computer simulation. A computational model can be used to make predictions of the ...

When you pee, not all the urine gets emptied from your bladder. If you have urinary problems, your doctor may need to know how much is left there. A post-void residual urine test can tell them. If the ...