TITLE: What is the actual meaning of runs in terms of coin tossing?
QUESTION [6 upvotes]: I am not able to understand the concept of runs in terms of coin tossing. As per my question, suppose a coin is tossed x times, then we have to find the expected number of runs.
But, what is a run? Can anybody give a detailed example?
As per the question, the sequence of tosses HHHHTTHTTTHHHTHH has 7 runs. How? I am really not able to understand. I researched and found somewhere that a run is when the previous outcome is different from current, so for this case, how will it apply?
Can somebody please explain in layman terms?
Thanks

REPLY [8 votes]: Take the full sequence and cut it at each point where there is a transition (next value is different from the previous one). Each part is a run.
 HHHHTTHTTTHHHTHH  =>  HHHH TT H TTT HHH T HH   => 7 runs

In other words, elaborating on Peter's answer, a run is a maximum-length subsequence of equal values.