Economic and Environmental Geology

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Table. 1.

Table. 1.

Notation of variables and parameters used in this study

Notation Value Description
Indices
d Index of documents
k Index of topics
t Index of years
In LDA
α 0.01 Dirichlet prior on the per-document topic distribution (hyperparameter)
η 0.1 Dirichlet prior on the per-topic word distribution (hyperparameter)
θd Topic distribution of document d
θd,k Distribution of topic k in document d
βk Word distribution of topic k
zd,n Topic assignment from θd in word n
wd,n Observed word n in document d
K 10 Number of topics
D 2,571 Number of documents
V 17,242 Number of unique words in the LDA vocabulary
N 314,248 Total number of words in all documents
Econ. Environ. Geol. 2021;54:353-64 https://doi.org/10.9719/EEG.2021.54.3.353
© 2021 Econ. Environ. Geol.