title_body: How to make good analogy in one's constructed language?
upvoted_answer: Let's look at a made-up example. Assume that we want to apply a sound change from /g/ to /d͡ʒ/ before /e/ and /i/ in Esperanto. Then, the conjugation of the Esperanto verb pagi "to pay" suddenly becomes irregular:
  
  paĝi, pagas, paĝis, pagos, pagus (The infinitive and the past tense have a different consonant (ĝ) than the rest).
  
  Analogy will force one consonant for all forms but we cannot predict which one. In this respect, analogy is quite irregular, and we can end up either with the original Esperanto paradigm, or with all forms shifted to the new consonant (paĝi, paĝas, paĝis, paĝos, paĝus).
  
  Analogy affects usually inflected or agglutinative word forms, such as verbs and nouns, but it can also be applied to derivational morphology.
  
  Another type of analogy tries to level out differences between conjugations or declensions. Assume, your language features two different conjugations. Than borrowing an ending (or prefix, or vowel change) from one conjugation to the other is also an analogy.