FreeExam

Transformers

An applied AI scientist interview on a transformer project: the block that was chosen, the data it saw, and what broke.

These prompts are original practice. They are not questions from a named employer or a live hiring loop.

  1. 1.The ticket encoder compared 4 layers at learning rate 3e-4 with 12 layers at learning rate 1e-5. Macro-F1 on the same tickets moved from 0.71 to 0.78. What does that pair support?

  2. 2.The speech transformer was retrained on 30-second clips instead of 4-second clips, and that same run switched from absolute sinusoids to rotary positions. Word error on the dev calls fell from 18.4 to 14.1. What is supported?

  3. 3.Catalog training text appended a merchant search-boost sentence from the ranking table. The product request sends title, brand, and attributes only. Category accuracy was computed on the training rows. What is wrong with that score?

  4. 4.Each clinical note had the diagnosis code appended after a separator. The attention mask used the note length and stopped at the separator, so the code tokens were never attended. Token accuracy on the note body stayed high. What did that run train?

  5. 5.Support chats were packed end to end to fill 2048 tokens. No block mask was applied. A boundary was only a special token. Loss on the packed dev set beat loss on single chats. What can that packed loss hide?

  6. 6.Monday's review-comment checkpoint was loaded for a demo. The tokenizer beside it was Thursday's vocab, which split identifiers differently and reused the same integer ids. What breaks when those weights score a diff?

  7. 7.Sensor traces were binned into tokens and trained with mean token loss. One device wrote a 40,000-token burst of irregular bins. Mean loss stayed near 4.8 while every other device sat near 1.1. What is that mean responding to?

  8. 8.Ticket text and labels both came from the week of 3 March. The holdout was a random 20 percent of that same week. Macro-F1 was 0.74. Which claim is out of reach?

  9. 9.The ticket encoder's accuracy was 0.94. Safety tickets were 1.2 percent of the file and their recall was 0.04. The dashboard ranked runs by accuracy. What does accuracy leave out?

  10. 10.Call transcription waits until the caller hangs up, then sends the whole clip. The team still trained a causal mask that hid every later frame inside that clip. Word error stayed high on words that are clear only after the next syllable. What did the mask discard?

  11. 11.Catalog pages were scraped with the markup left in. On a slice of errors, the largest attention weights sat on div and span tokens, not on brand or size. What did the data give the encoder?

  12. 12.The clinical label is the code that should have been known 24 hours after admission. Training notes were the full chart, including day-3 progress notes and the discharge summary. What did those later sections do?

  13. 13.The support model is supposed to predict the next agent reply. The gold reply was still in the packed context. The loss mask started one turn late, so those gold tokens remained visible to the query. Dev loss dropped sharply. What is the drop consistent with?

  14. 14.On the review model, an attention mask was added so the gold comment could not be seen. The length used for that mask was the comment length, and it was applied from the start of the row, which is the diff. Comment loss went to chance. What did the mask hide?

  15. 15.Plant sensors were reduced to 1-second means, then to 32 bins, then to a transformer. The fault label is a spike that lasts about 80 milliseconds. What can that pipeline do to the fault?

  16. 16.Before training, a triage tool wrote the queue name into the ticket subject, like "[billing] card declined". The encoder's queue head was trained on that full subject. What can the head do on those rows?

  17. 17.Overall word error on the speech dev set was 9.1. On the drug-name slice it was 41. A one-character miss on a drug name is a different drug. The weekly report quoted 9.1. What does 9.1 conceal?

  18. 18.Catalog rows were truncated to 128 tokens. Size, color, and material were the last attributes in the merchant's list. Errors piled up on those three fields. What did the cutoff remove?

  19. 19.Clinical notes and codes for the score all came from one ward during the week of 3 March. The holdout was a random fifth of that week. Note-level accuracy was 0.81. What can this project not claim?

  20. 20.Support intent accuracy was 0.93 by exact match on the reply class. Cancel-safety was 0.8 percent of chats and was never predicted. Exact match still rose when that class was dropped from the decode list. What did exact match ignore?

  21. 21.Review-comment BLEU against the human comment was 0.27 and was used to rank checkpoints. Security-severity comments were 2 percent of threads. A checkpoint that never emitted one still tied the BLEU leader. What did BLEU fail to see?

  22. 22.Sensor token accuracy was 0.97. The normal bin was 99 percent of tokens. The fault bin's recall was 0.02, and the on-call view ranked models by token accuracy. What does 0.97 reward?

  23. 23.Ticket batches were padded to the longest ticket in the batch. The padding id was 0, and the encoder was called without a pad mask. On short tickets, attention mass sat on the pad positions. What were those positions?

  24. 24.Speech training used 8 kHz audio with a 10 ms hop. The request path sends 16 kHz audio through the same hop and the same transformer. A token now covers a different amount of time. What else moved?

  25. 25.Catalog tokenization was compared as byte-pair encoding versus WordPiece. The WordPiece run also used learning rate 1e-5 instead of 3e-4. Category macro-F1 rose from 0.62 to 0.70. What can be attributed to the tokenizer?

  26. 26.One clinical note was a 20,000-token paste of raw lab tables. Mean token loss sat near 3.9, while the median note sat near 1.4. What is the mean mostly made of?

  27. 27.The support collator prepended a policy paragraph that the training job stored on disk. The customer-channel request does not include that paragraph. Intent accuracy was measured on collator output. What is that accuracy measuring?

  28. 28.Review training joined each author's past accept rate onto the front of the diff. The review service request contains the diff and the PR title, not that rate. A score computed on the joined rows looked strong. What is the gap?

  29. 29.Sensor training appended a maintenance flag from the work-order table, as the token MAINT or CLEAR. The live packet is the bin sequence only. Fault ranking was computed on the appended rows. What did the flag allow?

  30. 30.Reopened tickets kept the same ticket id and were randomly split. A parent in training and its reopen in the holdout shared the subject and the queue. Holdout accuracy was 0.91. What can that 0.91 include?

  31. 31.A long call was cut into 4-second chunks with absolute position ids starting at 0 on every chunk. The same spoken word landed on position 3 in one chunk and position 40 in the next. What do those two occurrences look like to the model?

  32. 32.The catalog label is the breadcrumb category. That breadcrumb was also written at the top of the text the encoder read. Category accuracy on that text was 0.96. What can the model do?

  33. 33.Clinical note accuracy was 0.84. On the slice whose assessment says "no evidence of" the target condition, accuracy was 0.31, and that slice was not in the weekly table. What did the 0.84 skip?

  34. 34.Support turns were concatenated with no speaker marker. The loss was next-token prediction on the whole chat. Samples often continued the customer instead of starting an agent reply. What did the data fail to mark?

  35. 35.Review rows were built by concatenating the diff and the full comment thread, including the comment the model was asked to write. Comment perplexity on those rows was low. What is the low perplexity consistent with?

  36. 36.Sensor devices were packed back to back in one 4096-token row so the batch would fill. There was no block mask. A fault token on device A was often followed by a correct prediction on device B's quiet trace. What can device B's prediction use?

  37. 37.The ticket model was trained with the queue logit read from the first token. The export averaged every token, including pads, and wrote that vector to the queue head. Short tickets moved the most. What changed at export?

  38. 38.Speech dev references were the previous model's transcripts, not a human pass. Word error against those references fell after the new transformer was warm-started from that previous model. What can that fall mean?

  39. 39.A parent SKU and its color variants shared one title. The split put the parent in training and a variant in the holdout. Title-based category accuracy was 0.93. What can the holdout row repeat?

  40. 40.Clinical notes were truncated to 512 tokens from the start. The assessment and plan sat at the end of long notes. Accuracy was high on short notes and near chance on notes longer than 512. What did the long notes lose?

  41. 41.Support reply perplexity fell from 11.2 to 7.4 after a longer training run. On the billing-intent slice, intent accuracy stayed at 0.52. The status note quoted the perplexity drop. What did perplexity not say?

  42. 42.A review training mix included one lockfile diff of about 100,000 lines. Mean token loss stayed high, and the gradient norm spiked on that row every epoch. Ordinary code diffs had small per-row loss. What is the update chasing?

  43. 43.A fault occurred only at site 7. Each sensor row started with a device id, and the id's prefix was the site. The transformer predicted the fault whenever the prefix was site 7, including on quiet traces from that site. What shortcut is available?

  44. 44.Two annotators labeled tickets. Training used the majority queue. The reported accuracy compared the model to the senior annotator alone, including rows where the senior was the minority. What can that accuracy punish?

  45. 45.The speech collator wrote a locale id token from the training manifest. The new phone client does not send locale. Word error was reported on collator batches that still had the token. What is that word error taken on?

  46. 46.Catalog prices were tokenized after the decimal point was stripped, so 19.99 and 1999 became the same digit pieces. The attribute head confused a price with a model number on that slice. What did stripping the decimal do?

  47. 47.Clinical de-identification was retagged between the training export and the serve path. Training used the literal NAME. Serving used [PERSON], which the clinical vocab had never split the same way. What changed for a patient's name?

  48. 48.One support transcript was an eight-hour dump of distinct error strings. It was kept in the training mix. Mean reply loss stayed near 6, while typical chats sat near 2. What is the mean mostly counting?

  49. 49.The review comment said getUserId, while the diff tokenized get_user_id into different pieces. The generated comment named getUserId on a hunk that only contained get_user_id. What did the two spellings become?

  50. 50.Bin edges for the sensor tokens were fit on the training week, which included one huge spike. After the fit, 98 percent of ordinary readings fell in a single bin. What did the spike do to the bins?

  51. 51.The ticket objective was a denoising loss on the body tokens. The queue head was attached, but its cross-entropy was scaled by 0.01 and was not in the early-stopping rule. Body loss fell. Queue macro-F1 did not. What was the optimizer mostly reducing?

  52. 52.The speech transformer was restored from Tuesday, and the k-means codebook that turns frames into token ids was refit on Wednesday. The same acoustic frame now maps to a new id, and Tuesday's embedding row still holds the old id's vector. What is mismatched?

  53. 53.A catalog checkpoint was trained with a 32,000-piece vocab. The file loaded at serve time had 32,400 pieces. The extra 400 product tokens had randomly initialized rows. What happens when a new product token appears?

  54. 54.ICD codes E11.9 and E11.65 were split into shared pieces. E11.9 was common and E11.65 was rare. The code head often emitted E11.9 on notes whose billed code was E11.65. What did the shared pieces allow?

  55. 55.The support eval set kept only chats the bot had already closed with "no action needed". Humans had not relabeled them. Intent accuracy on that set was 0.98. What population is that 0.98 about?

  56. 56.Python diffs were tokenized with a whitespace strip, so indentation tokens were deleted. Generated comments described a block that, in the stripped text, had merged with the surrounding block. What did the strip remove?

  57. 57.The sensor model is a next-hour fault forecast. At eval, the window included the hour being forecast, and the causal mask was left off. Token loss on that hour was very low. What could the model see?

  58. 58.Ticket early stopping watched accuracy. Across the last five checks, accuracy rose from 0.90 to 0.93 while safety recall fell from 0.22 to 0.07. The saved checkpoint is the last one. What did the stopping rule keep?

  59. 59.A speech run turned SpecAugment on and added four encoder layers in the same job. Word error fell from 16.0 to 13.5. The writeup credited the extra layers. What else changed in that job?

  60. 60.Catalog attributes were sorted alphabetically for training. The request sends them in the merchant's order. Positions were absolute. The same color token landed on different indices in the two paths. What do those indices do?

  61. 61.Clinical attention on correctly coded notes concentrated on the header token ASSESSMENT. A serving template emitted the same section without that header. Accuracy fell, and the note blamed the layer count. What did the template remove?

  62. 62.Support chats were truncated to the first 256 tokens. The customer's statement of the problem was often turn four or later, past the cutoff, while the greeting remained. Intent errors rose on long chats. What did the 256 tokens contain?

  63. 63.Code-review training kept diff headers such as @@ -20,4 +20,6 @@. The serving path stripped headers before tokenization. Comments that cited a line number degraded on the stripped path. What did training have that serving removed?

  64. 64.Sensor time is irregular. Gaps were filled with a GAP token, one per missing second. A quiet hour with a few real readings became thousands of GAP tokens. Mean loss tracked the GAP prediction. What did the fill do to the average?

  65. 65.New product names in the ticket file were labeled other. Accuracy counted other as a correct class. As new names arrived, other grew, and accuracy rose with it. What did that rise include?

  66. 66.A speech window often held two speakers, and no speaker token was added. The loss averaged frame tokens across both. Transcripts swapped a name from the second speaker into the first speaker's line. What did the average mix?

  67. 67.Catalog masked-token loss fell from 2.4 to 1.6. Category macro-F1 on the same items stayed at 0.58. The run was described as a better catalog model. What did the falling loss measure?

  68. 68.The clinical decision time is admission plus 24 hours. A creatinine value resulted on day 2 was still in the training note, and the code correlates with that value. What did the day-2 lab provide?

  69. 69.Support next-token accuracy counted every token, including the customer's. The agent is not supposed to emit the customer's words. Accuracy was 0.88, and most hits were on customer turns. What did 0.88 mostly score?

  70. 70.A review experiment added a second encoder for the PR title and cut the learning rate from 3e-4 to 1e-5 in that same job. Comment BLEU rose from 0.21 to 0.26. What can be credited to the title encoder?

  71. 71.Sensor normalization used a mean and variance computed with the outlier device included. That device's spike set the variance very high, so ordinary readings shrank toward zero before binning. What did the ordinary readings become?

  72. 72.A ticket run turned class weights on and raised dropout from 0.1 to 0.3 in the same job. Safety recall rose from 0.08 to 0.19. The note credited the class weights. What else changed?

  73. 73.The speech frontend was swapped from a 10 ms hop to a 30 ms hop, and the transformer checkpoint was kept. The same call now produces about a third as many frame tokens. What did the swap change for the transformer?

  74. 74.Catalog training text was source-language only. Requests began to include machine-translated titles, and no language token was added. Category errors rose on the translated titles. What was new in those requests?

  75. 75.Two patients' notes were packed into one row to fill the context. No block mask was used. A code that appeared only in patient A's note was predicted on patient B's positions. What could B's positions attend to?

  76. 76.Support chats for the score were a random 20 percent of the week of 3 March, the same week as training. The help-center article changed the following Monday. Intent accuracy that week was 0.86. What can 0.86 not support?

  77. 77.Review holdout threads were a random slice of one release branch during the training week. The spec phrases in that branch also appeared in training diffs. Comment scores looked strong. What can the project not claim from that slice?

  78. 78.Sensor holdout hours were random hours from the training week at site 7. A storm the next week changed the trace shape at that site, and site 9 was never in the file. What is out of reach?

  79. 79.Ticket probabilities for the head queue often sat near 0.99. Safety probabilities sat near 0.01. The decode rule fired a queue only above 0.5. Safety never fired. What did the 0.5 rule do to safety?

  80. 80.Silence in the speech tokens was a single repeated id. Frame accuracy was 0.95, and silence was most of the frames. On speech frames the accuracy was 0.61, which was not in the report. What did 0.95 mostly count?

  81. 81.To fill a catalog batch, the collator appended product B's description to product A's title in one row, with no boundary mask. The category label was A's. What could A's category positions attend to?

  82. 82.A clinical run continued pretraining on notes for three epochs and also cut the learning rate, then fine-tuned. Code accuracy rose versus a run that did neither. The note credited the extra pretraining. What else differed?

  83. 83.Support compared a decoder-only stack with an encoder-decoder stack. The decoder-only job also used learning rate 1e-5 instead of 3e-4. Reply intent accuracy rose by four points. What is isolated?

  84. 84.Review training diffs included a generated vendor directory. The human review request is the author's hunk only, and the vendor tree is not in that payload. Comments on the training rows often cited vendor files. What were those comments conditioned on?

  85. 85.Two sensor channels were concatenated into one token stream with no separator and no channel id. A spike on channel 1 was sometimes read as a spike on channel 2 after a small shift. What did the concatenation leave ambiguous?

  86. 86.The ticket form tokenized the product code ACME-440 as separate pieces. A catalog blurb joined at train time had already split that code under an older vocab, and both versions were concatenated. What did the row contain?

  87. 87.Speech byte-pair encoding was fit on studio transcripts. Phone-band names came apart into several pieces, while the same name was one piece in the studio text. The name slice suffered. What did the studio fit fail to keep intact?

  88. 88.Catalog macro-F1 was computed after classes with fewer than 10 items were dropped. Those dropped classes included the hazmat shelf. The remaining macro-F1 was 0.77. What happened to hazmat?

  89. 89.Clinical note accuracy was 0.88. The rare adverse-event code had recall 0.03 and was the code the safety review asked about. The status line quoted 0.88. What did 0.88 leave unstated?

  90. 90.Support inputs included the wrap-up field, where the agent typed the disposition code after the chat. The model was asked to predict that same code. Accuracy was high. What was in the input?

  91. 91.In review training, each comment quoted the line it discussed, and that quote was inside the input. Serving dropped the quote field and sent only the diff. Comments that had leaned on the quote degraded. What did serving remove?

  92. 92.A sensor run raised the head count from 4 to 8 and lengthened the learning-rate warmup from 1,000 to 8,000 steps in the same job. Fault recall rose. The note credited the extra heads. What else changed?

  93. 93.Ticket loss was averaged per token, not per ticket. A 2,000-token ticket outweighed a 40-token ticket by about fifty to one in the gradient. Queue errors on short tickets stayed high. What did the per-token mean favor?

  94. 94.A speaker was held out of the speech dev transcripts. That speaker's clips were still in the audio used to fit the k-means codebook that produces the frame tokens. What did the codebook fit already see?

  95. 95.The catalog style guide starts every title with the shelf name, and the shelf name is the label. Title accuracy was 0.95. What can a model read off the first tokens?

  96. 96.An addendum written after the clinical code was assigned was included in the training note. The addendum restates the code in prose. What can the encoder do with that addendum?

  97. 97.Support compared greedy decoding with a 4-best list and, in that same job, changed the temperature from 1.0 to 0.3. Intent match rose. The note credited the 4-best list. What else changed?

  98. 98.On the review model, new lines used relative positions and the deleted lines kept absolute ids from an older run. A comment that compared a deletion with its replacement mixed the two position schemes. What was inconsistent?

  99. 99.Sensor loss was a mean over tokens. Long quiet traces had thousands of easy normal tokens. Short fault events had a few dozen tokens. The mean looked healthy while faults were missed. What did the mean weigh most?

  100. 100.Billing and refund were separate ticket queues. Mid-week, the training file merged them into billing. The holdout file still used both queues. A refund ticket scored as a billing prediction counted as wrong. What disagreed?

  101. 101.Speech reporting used character error. A drug name that differed by one character from the reference stayed a small character error and was the wrong drug. The report quoted the character figure. What can that figure shrink?

  102. 102.Catalog training lowercased every string. The request preserves brand capitals, and the vocab has separate pieces for Acme and acme. Brand errors rose on the request path. What differed between the two paths?

  103. 103.Clinical sections were sorted alphabetically in the training export. The request sends chart order, with assessment last. Absolute positions were used. The assessment header moved to a new index at request time. What moved with it?

  104. 104.Support training targets were the agent's edited reply. The score compared the model's first draft with the customer's star rating, which the editors had not been asked to optimize. Star averages barely moved when intent match did. What was the score looking at?

  105. 105.Review token accuracy was 0.94, and most tokens were the diff, which the input already contained. Comment tokens were a small fraction of the loss. The diff was copied well and the comments were not. What did 0.94 mostly measure?

  106. 106.The sensor label is the alarm code. The PLC alarm string was already inside the token window the model read, ahead of the position being scored. Loss on the alarm code was very low. What could that low loss be?

  107. 107.A ticket run compared label smoothing on against label smoothing off, and the on job trained for six epochs while the off job trained for two. Tail recall was higher on the longer job. What can be attributed to smoothing?

  108. 108.Speech training used a 50 percent overlap between chunks, and the dev split was by chunk rather than by call. The same word from one call landed in a training chunk and a dev chunk. What can the dev chunk share with training?