Taken from an article in QST by William E. Packard, NN9U entitled: Morse Code: Efficient or Over the Hill? Unfortunately the article was not available for download so I will restate some of the article here and supply the lists that were in the article. Thanks to John WT7G for sending me the article.
Letters Appear in Groups
We learned in elementary school spelling class that letters in words appear in certain recurring patterns, not randomly. I remember in grade school being happy whenever there was an ING, OUGH or ER in a word, because those were word parts I could easily spell. Words have many more recurring patterns as a glance at the first sentence of this paragraph shows. That sentence has the letters IN appearing six times, the letters AR appearing three times and TT appearing twice with the double letters SS, LL, OO, RR and PP each appearing once. We ought to be able to exploit these recurring letters in our quest to learn the code, but how?
In principle the answer to this question is easy. If we knew all the recurring letters/words in the language, provided there were not too many of them, we could turn them into code and record them on a computer or CD and play them back until we knew them like familiar old friends. We would then be well on our way to learning high-speed code. But how can we find these recurring patterns?
Fortunately, there is a wealth of information on the subject of word and letter frequencies for both written and spoken English. Letter frequencies (the frequency with which each letter in the alphabet occurs in text) have been used by cryptographers to break substitution codes for centuries. In addition, frequency analysis for word and letter groups has been used by linguists for authorship analysis, to teach reading to children, to teach Braille and for the education of the deaf. List of frequent letter combinations and frequently used words are available.
A digraph is a single sound in speech that is represented by two letters such as TH in “path”. A trigraph is three such letters. The most common di and tri-graphs for the English language are listed below also included are the most frequently used double letters, the most common two, three and four letter words and finally the most common words used in the English language.
You can cut copy and past these into Just Learn Code to practice…
Most Common Digraphs (Listed in order of frequency)
TH HE AN IN ER ON RE ED ND HA AT EN ES OF NT EA TI TO IO LE IS OU AR AS DE RT VE SE OR AL TE CO
Most Common Trigraphs (Listed in order of frequency)
THE AND THA ENT ION TIO FOR NDE HAS NCE TIS OFT MEN ING EDT STH
Most Common Double Letters (Listed in order of frequency)
SS EE TT FF LL MM OO
Most Common Two-Letter Words (Listed in order of frequency)
OF TO IN IT IS BE AS AT SO WE HE BY OR ON DO IF ME MY UP AN GO NO US AM
Most Common Three-Letter Words (Listed in order of frequency)
THE AND FOR BUT NOT YOU ALL ANY CAN HAD HER WAS ONE OUR OUT DAY GET HAS HIM HIS HOW MAN NEW NOW OLD SEE TWO WAY WHO BOY DID ITS LET PUT SAY SHE TOO USE
Most Common Four-Letter Words (Listed in order of frequency)
THAT WITH HAVE THIS WILL YOUR FROM THEY KNOW WANT BEEN GOOD MUCH SOME TIME VERY WHEN COME HERE JUST LIKE LONG MAKE MANY MORE ONLY OVER SUCH TAKE THAN THEM WELL WERE
Most Common Words in the English Language (In alphabetical order)
A ABOUT AFTER ALL AN AND AM ARE AS AT
BACK BE BECAUSE BEEN BEFORE BEING BETWEEN BIG BUT BY
CAME CAN COULD COUNTRY
DAY DAYS DEBT DID SO DOLLARS DOWN
FIRST FOR FOUND FROM
GENERAL GET GO GOING GOOD GOT GREAT
HAD HAS HAVE HE HER HERE HIM HIS
I IF IN INTEREST INTO IS IT ITS
LARGE LAST LIKE LITTLE LOOK
MADE MAKE MANY MAY ME MORE MOST MUST MY
NEW NO NOT NOW
OF OFF ON ONE ONLY OR OTHER OUR OUT OVER
SAID SAW SEE SHE SINCE SO SOME STILL SUCH
TAKE THAN THAT THE THEIR THEM THEN THERE THESE THEY THOUGH TIME TO TODAY TWO
UNDER UP UPON
WAR WAS WE WELL WENT WERE WHAT WHEN WHERE WHICH WHILE WHO WILL WITH WOULD
YEARS YOU YOUR