My efforts paid off and I passed the exam.
This book was worth reading.
Even though I paid a lot of money, it was completely worthless.
価値 is the general word for worth or value of anything, while 甲斐 specifically means the rewarding result that makes an effort feel worthwhile.
効果 refers to an objective effect or result, while 甲斐 highlights the subjective sense of satisfaction gained from making an effort.
甲斐 (as the suffix ～がい, e.g. やりがい) and 応え (as in やり応え) both attach to verb stems to mean 'worth doing', though がい is somewhat more common in casual speech.
rewarding feeling; sense of fulfillment; worthwhile effort
good-for-nothing; spineless; pathetic; disappointing
resourcefulness; ability to get things done; dependability
one's age; age-appropriate behavior
brisk and efficient; diligent; devoted; spirited
Standard ateji spelling; the most common written form.
Kana spelling is common in everyday writing, especially in the phrase 〜したかいがある.
Rarely used kanji form.
Rarely used kanji form.
The historical derivation is uncertain. The kanji 甲斐 is an ateji (phonetic) spelling, and the word is considered a native Japanese term.
worthless; pointless; useless
worth mentioning; worth saying
worth talking to; rewarding to talk with
reliability; dependability; trustworthiness
good-for-nothing; useless person