President Palin? Flip a Coin.
Presidential running mates are often chosen not for their leadership abilities or understanding of the issues, but as a way to "complete" the candidate's image to voters by complementing some of their better qualities, or ameliorating their weaknesses. It's like picking out a necktie that makes your eyes look really good, only the necktie walks around the country saying nice things about you. As a result, voters forget that the Veep has the very real duty to lead the country if the President dies or is removed from office. 1 out of every 5 Presidents in this country has failed to complete his term due to natural death, assassination, or the threat of impeachment. Each time, a formerly powerless Vice President suddenly found himself in charge of, well, everything. This could very easily happen again.
Consider Senator Obama, male, 47 years old. Actuaries tell us that your average 47-year-old man today has a 5% chance of dying before Inauguration Day 2017, the end of a two term presidency. [1] However, in addition to natural death, 1 in 10 Presidents has been assassinated, and there always exists a tiny risk of impeachment. [2] Though young, Senator Obama, if elected for two terms, has a 16% chance of not making it. If Obama is elected President, Senator Biden will probably never do more than advise and assist the President, but at 16%, you'd better hope that this talking necktie is ready to run and defend the country. Just in case.
With Senator McCain, the numbers are a lot higher than the 1 in 3 that's being reported by most media outlets. True, your average 72 year-old man only has a 37% chance of dying before 2017. However, the risk of assassination or impeachment increases that number to 45%. Additionally, about a quarter of people in their late 70s suffer some cognitive difficulties.[3] Sadly, there is about a 9% chance that a sharp-witted 72-year-old man will develop moderate to severe cognitive impairment by the time he turns 80. [4] If Senator McCain tries for two full terms in office, there is only a 51% chance that he makes it through alive, unimpeached, and with most of his mental faculties intact. That would give Governor Palin a 49% chance of becoming the next, next president of the United States.
This is not to say voters should make their decisions based on the probability that a candidate could die in office. However, given the very real chance that Senator Biden or Governor Palin could become the President of the United States, America has to take a good look at each of them, and ask themselves, "Do I want this person running this country?" For Senator Biden, the chances are one in six. For Governor Palin, flip a coin.
[1] http://www.ssa.gov/OACT/STATS/table4c6.html
2 4 out of 43 presidents assassinated, Nixon forced out http://en.wikipedia.org/wiki/List_of_Presidents_of_the_United_States
3 See Chrislopher M. Callahan, MD; Hugh C. Hcndric, MB. ChB; and William M. Tierney. MD, Documentation and Evaluation of Cognitive Impairment
in Elderly Primary Care Patients Ann Intern Med. 1995:122:422-429 (27.3% of people in their late 70s experience mild to severe cognitive impairment);
4 See Hugh C. Hendrie, M.B., Ch.B., Epidemiology of Dementia and Alzheimer's Disease, Am J Geriatr Psychiatry 6:S3-S18, May 1998 (4.7% of people 71-75 moderately to severely impaired, 13.6% of people 76-80, 20.1% of people 81-85, implies roughly 8.9% of 76-80 year olds were not moderately to severely impaired in their early 70s); see also Mayo Clinic Study of Aging, (about 3.5% of individuals in their 70s developed mild cognitive impairment after one year. Based on that number, Senator McCain would have about a 27% chance of developing at least mild cognitive impairment by his 80th birth day. Rates for men are twice as high as rates for women. The calculation of 49% is based on Senator McCain's risk of "moderate to severe" cognitive impairment) http://seniorjournal.com/NEWS/Alzheimers/2008/20080729-MayoClinicFinds.htm