**Overall, the table is structurally clean, with a few real quality issues. I found no mixed units or inconsistent formats, and no physically impossible values.** **What is clean** - **Keys:** All 4,500 rows have a unique, non-null `Student_ID`. Every ID is 11 characters long, running from STU_2024000 to STU_2028499. - **Ranges:** All numeric columns sit in plausible ranges: - Age: 15–26. - Daily usage: 0.9–14 h. - Weekend extra hours: 0–4.5. - Sleep: 3–10.5 h. - Sleep quality: 1–5. - Mental health index: 32–98. - Stress: 0–40. - GPA: 1.9–4.0. - **Time budget:** No row has daily usage plus sleep above 20 hours (0 rows). - **Nulls:** There are none in the categorical columns, `Mental_Health_Index`, sleep or usage. - **Units and formats:** Every column has a single numeric or boolean type, and I saw no sign of mixed units. **Issues found** 1. **Age conflicts with academic level.** 156 of the 1,477 High School students (about 10.6%) are aged 19 or older, which is unusual for high school. Postgraduates aged 20 or under and undergraduates aged 16 or under are both zero, so the conflict runs one way. Either the level label or the age is likely wrong, or these are legitimate older or late-finishing students. 2. **Missing values in two measures.** - `Academic_Performance_GPA` is null in 85 rows (1.9%). - `Perceived_Stress_Score` is null in 46 rows (1.0%). - Averages and correlations on these columns silently drop those rows. 3. **Ceiling clipping on GPA.** 353 rows (about 8%) sit exactly at 4.0, which looks like a cap rather than a natural distribution. It will understate the true spread at the top and weaken correlations with GPA. 4. **Possible default or placeholder stress scores.** - 87 rows have a stress score of exactly 0, which is an implausible score for a real stress questionnaire. It may be a default fill or a data-entry artefact rather than a true measurement. - 8 rows are exactly 40, the maximum. 5. **Boundary values (possible clipping).** - Daily usage is capped at exactly 14.0 h in 55 rows, and 126 rows are at 12 h or more, so those long-usage entries are worth treating as potential outliers or clipped values. - Sleep is floored at exactly 3.0 h in 11 rows and sits at the 10.5 h maximum in 1 row. 6. **Soft missingness in `Gender`.** "Prefer not to say" has 93 rows and "Non-Binary" has 122. The small groups make subgroup statistics unstable, and "Prefer not to say" is effectively missing. 7. **Heavily imbalanced categories.** These distort naive comparisons: - `Overall_Impact` is 3,681 Beneficial, 654 Neutral and 165 Negative. - Smartphone accounts for 3,775 of 4,500 device types. - Postgraduates number only 246. - LinkedIn has 96 rows, and X (Twitter) has 206. **Recommendation:** Treat the 4.0 GPA ceiling, the 0 stress scores and the 14 h usage cap as censored or suspect values in any modelling. Decide whether to impute or exclude the 85 GPA and 46 stress nulls. Flag the 156 older High School rows for review. Be cautious with subgroup conclusions drawn from the small categories.