[R] Offtopic, HT vs. HH in coin flips
Erik Iverson
eiverson at NMDP.ORG
Mon Aug 31 21:16:33 CEST 2009
Dear R-help,
Could someone please try to explain this paradox to me? What is more likely to show up first in a string of coin tosses, "Heads then Tails", or "Heads then Heads"?
##generate 2500 strings of random coin flips
ht <- replicate(2500,
paste(sample(c("H", "T"), 100, replace = TRUE),
collapse = ""))
## find first occurrence of HT
mean(regexpr("HT", ht))+1 #mean of HT position, 4
## find first occurrence of HH
mean(regexpr("HH", ht))+1 #mean of HH position, 6
FYI, this is not homework, I have not been in school in years. I saw a similar problem posed in a blog post on the Revolutions R blog, and although I believe the answer, I'm having a hard time figuring out why this should be?
Thanks,
Erik Iverson
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