What is Test set?Test set kya hai?

🧸 Think of it likeAise samjho

Like the final exam paper kept sealed until the end, so nobody can practise on it.Final exam paper jaisa jo aakhir tak seal rehta hai, taaki koi uspe practice na kar sake.

📘 ExplainedVistaar se

Never train or tune on the test set; use it once for the final number. For time based data, the test set should be the most recent period. If you peek repeatedly, scores become too optimistic.Test set pe kabhi train ya tune mat karo; final number ke liye ek baar use karo. Time based data mein test set sabse haal ka period hona chahiye. Baar baar jhaankoge to scores zyaada optimistic ho jaate hain.

💡 Real exampleAsli example

Training on 2023 to 2025 data and testing on the first half of 2026.2023 se 2025 ke data pe training aur 2026 ki pehli chhamahi pe testing.

📖 Learn it step by stepStep by step seekho

• Train/test split and overfittingTrain/test split aur overfitting

🔗 Related termsJude hue shabd

• Validation setData used while building a model to compare options and tune settings.Model banate waqt options compare karne aur settings tune karne ke liye data.
• OverfittingWhen a model memorises its training data, including noise, and does badly on new data.Jab model training data ko, noise samet, ratt leta hai aur naye data pe kharab karta hai.
• Data leakageWhen information that won't exist at prediction time sneaks into training, making test scores falsely high.Jab prediction ke time na hone wali information training mein ghus jaati hai, aur test scores jhooth mein ooche aate hain.