Microsoft·Data Scientist·Technical Phone Screen
May 2026
Technical screen for a Data Scientist role at Microsoft. One question, but it was a beast: a four-part deep dive on CNNs, RNNs, and LSTMs that covered theory, math, parameter counting, and experimental design all in one shot. Left feeling like I'd taken an exam.
- Compare CNNs, RNNs, and LSTMs for sequence modeling across four dimensions: (1) inductive biases and when you'd prefer a dilated 1D CNN vs. RNN/LSTM, and when LSTM beats vanilla RNN; (2) the math behind vanishing/exploding gradients in vanilla RNNs and how LSTM gates address it; (3) parameter counts and parallelism tradeoffs for a 1D CNN, GRU, and LSTM given a specific input shape; (4) how you'd design an ablation study to pick among these models under tight latency and limited labeled data constraints.
“This was basically four questions stapled together and I did not clock that until I was already halfway through part one.” The rest of the author's notes on Data Scientist interview at Microsoft, Technical Phone Screen round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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