By the mid-1960s unilateral deterrence gave way to 'mutual deterrence', a situation of strategic stalemate. The superpowers would refrain from attacking each other because of the certainty of mutual assured destruction, better known as MAD. This theory is still a major part of the defense policies of the United States and Russia. This led to the foundation of the nuclear triad, or use of three different types of delivery systems (bombers, missiles, and submarines), to assure that a second-strike capability existed able to cause massive destruction to the attacking nation.
What costs do they measure? The difference between cost per thousand (CPM) and cost per rating point (CPRP) is that CPM measures the dollar cost of reaching 1,000 members of the media vehicle's audience. CPRP is a relative measure of the efficiency of a media vehicle to a firm's target market.
Characters per minute is often used as a metric because the name ignores the length of the words on the typing test. Someone who is typing lots of short, easy to spell words would perform faster than someone who types long, hard to spell words if you are counting words as a unit. A professional or good typist hits around 325 to 335 CPM.