I am presently using a skip/shift-of-one transposition equidistant letter sequence in an effort to decrypt possible intentionally placed letter-string words/phrases in the plaintext of one of Shakespeare's sonnets. I found, at an els of 14, a vertical letter string touching a horizontal phrase ("My name's . . . ") that says "DEVERE" which reads from bottom to top.
In calculating raw probabilities, the total number letters in the plaintext (sonnet, not including the spaces or punctuation) is/was the sample space. I got a letter frequency count for "DEVERE": Total Letters: 448 Letter-String: “DEVERE”:

Total Letters:  448        Letter-String:   DEVERE  =

(D = 27)  (E = 57)  (V = 8)  (E = 56)  (R = 24)  (E = 55) =  .00091010304/7817.48583804 = 1/8,589,971 =  .00000011641 =
11641/100,000,000,000 = 1 in 8,590,327 =   99.999988% raw probability of deliberate placement within the Plaintext.  

Is this a correct way of doing this? I realize there are several algorithms that can be used, but this one is relatively straightforward.

Jim (I am not a mathematician or statistician)