T-61.5020 Statistical Natural Language Processing
Exercises 6 -- Collocations
Version 1.0

You can choose a subset of words for the exercise.

1.
In Table 1 there is frequencies of several word pairs. Calculate the best candidates for collocations using the frequency method. Are the results better if you normalize the number of bigrams by the product of the number of its components?

2.
Calculate the mean and variance for the place of occurrence for some word pairs in the table. Judge how well those can be used for determining collocations. How does the window size affect results? The given statistics were counted over a window of five words.

3.
Use t-test and Pearson's chi-square test do determine whether the words pairs are collocations. Compare the results.

4.
Find collocations using mutual information and compare to the previous results.

 hakea työ 10435 26174 31 26 22 11 valkoinen talo 3665 10767 710 2 1 6 herne nenä 115 974 3 0 0 0 ja olla 818046 1387476 7329 39979 3612 38162 venäjä presidentti 27637 26855 717 216 10 24 vihainen mielenosoittaja 589 1757 7 0 0 0 tuntematon sotilas 1967 4806 154 4 0 0 aste pakkanen 2879 1440 160 8 13 32 heittää veivi 8126 21 5 0 0 1 kova tuuli 20613 3916 279 16 9 12 liukas keli 735 728 106 2 3 7 sekä myös 50193 135637 138 124 34 244 oppia lukea 2831 8952 21 4 7 1 olla ula 1387476 44 3 2 1 2 ottaa onki 38304 110 9 3 0 0

Some translations:

• hakea = apply for, työ = job
• valkoinen = white, talo = house
• herne = pea, nenä = nose, ``herne nenässä'' = ``pissed off''
• ja = and, olla = be
• Venäjä = Russia, presidentti = president
• vihainen = angry, mielenosoittaja = demonstrator
• tuntematon = unknown, sotilas = soldier
• aste = degree, pakkanen = frost
• heittää = throw, veivi = crank, ``heittää veivinsä'' = ``kick the bucket''
• kova = hard, tuuli = wind
• liukas = slippery, keli = weather, conditions
• sekä = as well as, myös = also
• oppia = learn, lukea = read
• olla = be, ULA = VHF, ``olla ulalla'' = ``be confused''
• ottaa = take, onki = hook and line, ``ottaa onkeensa'' = ``learn one's lesson''

svirpioj[a]cis.hut.fi