Across both Google and IBM certification assessments, the highest-frequency topics are: (1) SQL — SELECT, JOIN, GROUP BY, filtering, aggregations; (2) Python for data manipulation — pandas DataFrames, filtering, merging, handling missing values; (3) Statistics — mean, median, standard deviation, correlation, basic probability, hypothesis testing (p-value, t-test); (4) Machine learning — linear regression, logistic regression, decision trees, train/test split, confusion matrix, accuracy vs precision/recall; (5) Visualization — choosing the right chart type, reading matplotlib/Tableau outputs, communicating findings. BlitzGrok organizes practice by these domains so you can target your weakest areas first.