Panel-ready Data Science track questions for freshers and experienced developers. Practice at Coding Cadre in Faridabad, or Online from Delhi NCR.
Mean is the average.
Open the full page for Why, Steps, Example and Key takeaway.
A DataFrame is a labeled table with rows and columns, like Excel in code.
Open the full page for Why, Steps, Example and Key takeaway.
I first ask why data is missing.
Open the full page for Why, Steps, Example and Key takeaway.
It measures spread around the mean.
Open the full page for Why, Steps, Example and Key takeaway.
Selection bias means the sample does not represent the population you care about.
Open the full page for Why, Steps, Example and Key takeaway.
It keeps all left rows and matching right rows, with nulls when no match.
Open the full page for Why, Steps, Example and Key takeaway.
Histograms show distribution of a numeric variable in bins.
Open the full page for Why, Steps, Example and Key takeaway.
It shows median, quartiles, and outliers quickly.
Open the full page for Why, Steps, Example and Key takeaway.
You only analyze winners still visible — failed cases disappear.
Open the full page for Why, Steps, Example and Key takeaway.
Duplicates inflate counts and leak between train and test if not handled.
Open the full page for Why, Steps, Example and Key takeaway.
Correlation is association
Open the full page for Why, Steps, Example and Key takeaway.
Shape, dtypes, missingness, obvious outliers, and a few value counts.
Open the full page for Why, Steps, Example and Key takeaway.
Running many tests until one looks significant.
Open the full page for Why, Steps, Example and Key takeaway.
GROUP BY email or phone HAVING COUNT(*) > 1, then investigate.
Open the full page for Why, Steps, Example and Key takeaway.
Comparing magnitudes across categories.
Open the full page for Why, Steps, Example and Key takeaway.
Clear metric, sample size, runtime, and guardrails.
Open the full page for Why, Steps, Example and Key takeaway.
Volume, null-rate, and distribution monitors with alerts.
Open the full page for Why, Steps, Example and Key takeaway.
They run faster than Python row loops on large frames.
Open the full page for Why, Steps, Example and Key takeaway.
Lead with the decision, then evidence, then caveats.
Open the full page for Why, Steps, Example and Key takeaway.
Drop when rare and random
Open the full page for Why, Steps, Example and Key takeaway.