✅ Simple Trick to Identify:

👉 Question or hypothesis मा "greater than", "less than", "more than", "less than or equal to" जस्तो directional शब्द आयो भने — One-tailed test
👉 Question मा "not equal to", "different from" भनेको छ भने — Two-tailed test

📌 Example ले बुझौं:

1. One-Tailed Test (एक-तर्फी परीक्षण)

🗣 "Is the average salary greater than $500?"
👉 यहाँ “greater than” direction देखिन्छ — यसले right-tailed test जनाउँछ (because we are testing for increase only).
✅ One-tailed test

🗣 "Is the failure rate less than 5%?"
👉 “less than” direction देखाउँछ — यसले left-tailed test जनाउँछ (because we are testing for decrease only).
✅ One-tailed test

2. Two-Tailed Test (दुई-तर्फी परीक्षण)

🗣 "Is there any difference between male and female height?"
👉 यहाँ कुनै direction छैन — just "difference" भनेको छ।
✅ Two-tailed test

🗣 "Is the mean NOT equal to 100?"
👉 "Not equal to" भनेको मतलब हामी दायाँ र बायाँ दुवै पक्ष जाँच्दैछौं।
✅ Two-tailed test

💡 Summary:

थप सजिलो सम्झनाः
👉 Direction छ भने One-tailed
👉 Direction छैन भने Two-tailed