Recently I gave interview for Adtech Data Science team. The interview process took about 2 months. First round was basic statistics, probability and machine learning questions like 1.what is random forest 2.what are the parmaeters to tune, what is the difference between random forest and xgboost. 3. What is the imputation methods? mean, median, mode 4. One probability question based on cards conditional probability 5. Project based questions. 6. Pros and cons of random forest and xgboost? 7. Why did you prefer xgboost over random forest 8. Bias variance tradeoff. Underfitting and overfitting, precision, recall, auc roc curve - how will you choose the threshold. 9. Stats question - distribution 2 round - Indepth ML and Deeplearning questions 1. Xgboost parameters 2. explain boosting and bagging - pros and cons 3. Deep learning questions - rnn, cnn 4. Nlp - bert, llm, lora, qlora, finetuning 3 round - Indepth questions Design of cold start ad recommendation system. some project based questions, underfitting and overfitting, bagging and boosting, hyperparameter tuning, python question to find the top 10 customers who had purchased last month with discount. 4 ROUND - Hiring manager round Director interview in which he asked about weigheted quantile sketch algorithm in boosting xgboost. asked about scenarios where L1 and l2, Elastic net regularization are used. bias variance tradeoff. How random forest is prone to overfitting? pros and cons. Mathematically explain how transformers model works. Overall the interview process was difficult. Had to follow up with HR several times as they were irresponsive. After clearing all the rounds, HR asked for the documents. Then director wanted to have another round of technical interview it seems. The fifth round was very tough. The interviewer asked mathmetical derivation for each and every ML algorithm. Was very rude and cut the call abruptly. Till now I didn't receive any update from HR side and they ghosted me completely. Advice to Walmart HR and Interview team: If you don't want to select a candidate, please dont waste their time. HR team is very irresponsive, atleast give an update about the status of the interview.