Tachelhit — Full Ablation Study & Research Report
Detailed evaluation of all model variants trained on Tachelhit Wikipedia data by Wikilangs.
📋 Repository Contents
Models & Assets
- Tokenizers (8k, 16k, 32k, 64k)
- N-gram models (2, 3, 4, 5-gram)
- Markov chains (context of 1, 2, 3, 4 and 5)
- Subword N-gram and Markov chains
- Embeddings in various sizes and dimensions (aligned and unaligned)
- Language Vocabulary
- Language Statistics
Analysis and Evaluation
- 1. Tokenizer Evaluation
- 2. N-gram Model Evaluation
- 3. Markov Chain Evaluation
- 4. Vocabulary Analysis
- 5. Word Embeddings Evaluation
- 6. Morphological Analysis (Experimental)
- 7. Summary & Recommendations
- Metrics Glossary
- Visualizations Index
1. Tokenizer Evaluation
Results
| Vocab Size | Compression | Avg Token Len | UNK Rate | Total Tokens |
|---|---|---|---|---|
| 8k | 3.017x | 3.02 | 1.3938% | 408,453 |
| 16k | 3.301x | 3.30 | 1.5252% | 373,263 |
| 32k | 3.557x | 3.56 | 1.6432% | 346,460 |
| 64k | 3.819x 🏆 | 3.82 | 1.7643% | 322,672 |
Tokenization Examples
Below are sample sentences tokenized with each vocabulary size:
Sample 1: Sstekk iga yan ugḍiḍ imẓẓin. Assaɣ Tuzduɣt Tasnalɣa (morphologie) Tisaɣulin Msmu...
| Vocab | Tokens | Count |
|---|---|---|
| 8k | ▁s ste kk ▁iga ▁yan ▁ugḍiḍ ▁imẓẓin . ▁assaɣ ▁tuzduɣt ... (+19 more) |
29 |
| 16k | ▁s ste kk ▁iga ▁yan ▁ugḍiḍ ▁imẓẓin . ▁assaɣ ▁tuzduɣt ... (+19 more) |
29 |
| 32k | ▁s stekk ▁iga ▁yan ▁ugḍiḍ ▁imẓẓin . ▁assaɣ ▁tuzduɣt ▁tasnalɣa ... (+18 more) |
28 |
| 64k | ▁sstekk ▁iga ▁yan ▁ugḍiḍ ▁imẓẓin . ▁assaɣ ▁tuzduɣt ▁tasnalɣa ▁( ... (+17 more) |
27 |
Sample 2: Asimwas iga ass wiss Smmus g ussan n imalass. Tisaɣulin
| Vocab | Tokens | Count |
|---|---|---|
| 8k | ▁as im was ▁iga ▁ass ▁wiss ▁smmus ▁g ▁ussan ▁n ... (+3 more) |
13 |
| 16k | ▁as imwas ▁iga ▁ass ▁wiss ▁smmus ▁g ▁ussan ▁n ▁imalass ... (+2 more) |
12 |
| 32k | ▁asimwas ▁iga ▁ass ▁wiss ▁smmus ▁g ▁ussan ▁n ▁imalass . ... (+1 more) |
11 |
| 64k | ▁asimwas ▁iga ▁ass ▁wiss ▁smmus ▁g ▁ussan ▁n ▁imalass . ... (+1 more) |
11 |
Sample 3: Turdut (S turdut: اردو ) tga tutlayt nna s sawaln ayt Bakistan d Lhnd. Isuɣal
| Vocab | Tokens | Count |
|---|---|---|
| 8k | ▁tur dut ▁( s ▁tur dut : ▁ا ر دو ... (+14 more) |
24 |
| 16k | ▁tur dut ▁( s ▁tur dut : ▁ار دو ▁) ... (+13 more) |
23 |
| 32k | ▁turdut ▁( s ▁turdut : ▁اردو ▁) ▁tga ▁tutlayt ▁nna ... (+9 more) |
19 |
| 64k | ▁turdut ▁( s ▁turdut : ▁اردو ▁) ▁tga ▁tutlayt ▁nna ... (+8 more) |
18 |
Key Findings
- Best Compression: 64k achieves 3.819x compression
- Lowest UNK Rate: 8k with 1.3938% unknown tokens
- Trade-off: Larger vocabularies improve compression but increase model size
- Recommendation: 32k vocabulary provides optimal balance for production use
2. N-gram Model Evaluation
Results
| N-gram | Variant | Perplexity | Entropy | Unique N-grams | Top-100 Coverage | Top-1000 Coverage |
|---|---|---|---|---|---|---|
| 2-gram | Word | 1,027 | 10.00 | 23,244 | 45.7% | 81.7% |
| 2-gram | Subword | 255 🏆 | 7.99 | 3,782 | 68.8% | 99.0% |
| 3-gram | Word | 1,698 | 10.73 | 46,062 | 39.0% | 76.4% |
| 3-gram | Subword | 1,284 | 10.33 | 29,101 | 35.1% | 84.7% |
| 4-gram | Word | 3,109 | 11.60 | 90,318 | 35.2% | 68.9% |
| 4-gram | Subword | 3,345 | 11.71 | 117,821 | 23.5% | 73.6% |
| 5-gram | Word | 3,900 | 11.93 | 100,607 | 35.2% | 65.7% |
| 5-gram | Subword | 5,689 | 12.47 | 238,898 | 18.6% | 68.5% |
Top 5 N-grams by Size
2-grams (Word):
| Rank | N-gram | Count |
|---|---|---|
| 1 | tgmiḍi n |
30,047 |
| 2 | n usggʷas |
27,406 |
| 3 | umḍan n |
26,921 |
| 4 | n imzdaɣn |
25,250 |
| 5 | tlkm tgmiḍi |
24,096 |
3-grams (Word):
| Rank | N-gram | Count |
|---|---|---|
| 1 | tlkm tgmiḍi n |
24,096 |
| 2 | tamattayt n usɣiws |
16,122 |
| 3 | tasmirit tamattayt n |
15,740 |
| 4 | umḍan n imzdaɣn |
14,946 |
| 5 | g tlkm tgmiḍi |
12,050 |
4-grams (Word):
| Rank | N-gram | Count |
|---|---|---|
| 1 | tasmirit tamattayt n usɣiws |
15,739 |
| 2 | g tlkm tgmiḍi n |
12,050 |
| 3 | ad i trfiqt n |
8,924 |
| 4 | uḍwwaṛ ad i trfiqt |
8,917 |
| 5 | umḍan n imzdaɣn nns |
8,916 |
5-grams (Word):
| Rank | N-gram | Count |
|---|---|---|
| 1 | uḍwwaṛ ad i trfiqt n |
8,916 |
| 2 | n imzdaɣn tasmirit tamattayt n |
8,910 |
| 3 | amatay n imzdaɣn tasmirit tamattayt |
8,910 |
| 4 | imzdaɣn tasmirit tamattayt n usɣiws |
8,910 |
| 5 | ilkm umḍan n imzdaɣn nns |
8,904 |
2-grams (Subword):
| Rank | N-gram | Count |
|---|---|---|
| 1 | n _ |
653,950 |
| 2 | _ n |
401,960 |
| 3 | _ t |
358,450 |
| 4 | _ i |
253,361 |
| 5 | t a |
205,185 |
3-grams (Subword):
| Rank | N-gram | Count |
|---|---|---|
| 1 | _ n _ |
294,525 |
| 2 | _ t a |
132,562 |
| 3 | n _ t |
104,642 |
| 4 | a n _ |
103,515 |
| 5 | _ ɣ _ |
101,882 |
4-grams (Subword):
| Rank | N-gram | Count |
|---|---|---|
| 1 | _ n _ u |
84,436 |
| 2 | t _ n _ |
67,385 |
| 3 | _ n _ i |
61,498 |
| 4 | _ n _ t |
56,134 |
| 5 | n _ u s |
52,239 |
5-grams (Subword):
| Rank | N-gram | Count |
|---|---|---|
| 1 | _ n _ u s |
51,413 |
| 2 | m z d a ɣ |
46,710 |
| 3 | g g ʷ a s |
34,963 |
| 4 | s g g ʷ a |
34,938 |
| 5 | _ n n a _ |
34,315 |
Key Findings
- Best Perplexity: 2-gram (subword) with 255
- Entropy Trend: Decreases with larger n-grams (more predictable)
- Coverage: Top-1000 patterns cover ~68% of corpus
- Recommendation: 4-gram or 5-gram for best predictive performance
3. Markov Chain Evaluation
Results
| Context | Variant | Avg Entropy | Perplexity | Branching Factor | Unique Contexts | Predictability |
|---|---|---|---|---|---|---|
| 1 | Word | 0.6330 | 1.551 | 4.06 | 76,272 | 36.7% |
| 1 | Subword | 1.2927 | 2.450 | 10.38 | 804 | 0.0% |
| 2 | Word | 0.2598 | 1.197 | 1.65 | 308,953 | 74.0% |
| 2 | Subword | 1.0716 | 2.102 | 6.52 | 8,341 | 0.0% |
| 3 | Word | 0.0840 | 1.060 | 1.19 | 508,729 | 91.6% |
| 3 | Subword | 0.8300 | 1.778 | 3.82 | 54,358 | 17.0% |
| 4 | Word | 0.0475 🏆 | 1.033 | 1.13 | 601,513 | 95.2% |
| 4 | Subword | 0.5642 | 1.479 | 2.43 | 207,789 | 43.6% |
Generated Text Samples (Word-based)
Below are text samples generated from each word-based Markov chain model:
Context Size 1:
n twtmin ɣ tsga n lfṛaṛḥa nna mi ilkm umḍan n ayt ɛli n tarskkilt 43ɣ tmnaḍt n urtzaɣ taḍwwaṛḍt n tarwuri 2 aslmd g tlkm tgmiḍi n ism n isrɣinnd ublulls dar gr d lli tmmal tflwit yaḍn ngr adrar n bni matar m sidi
Context Size 2:
tgmiḍi n tarskkilt 70 82 gr mddn nna dar gr 6 d 11 n usggʷas niɣ uggarn usggʷas 28 48 dar tsdnan 3 5 aslmd g tlkm tgmiḍi n 35 1 ig unammasumḍan n imzdaɣn n lmɣrib ɣ tsga n trudant n fas amknas ɣ lmɣrib iḍfaṛ uḍwwaṛ ad
Context Size 3:
tlkm tgmiḍi n uslmd 91 97 gr irban d trbatin nna dar gr 6 d 11 n usggʷastamattayt n usɣiws aṛcif 14 ɣuct tisnaddadin tisnaddadin timatayin iggʷiz umḍan n imzdaɣn n tamyawas...tasmirit tamattayt n usɣiws tisaɣulin isɣwan yaḍnin tasmirit tamattayt n usɣiws ɣ iga umḍan n imawaḍ...
Context Size 4:
tasmirit tamattayt n usɣiws aṛcif 14 ɣuct tisnaddadin tisnaddadin timatayin iɣli umḍan n imzdaɣn n a...g tlkm tgmiḍi n uslmd 98 7 gr irban d trbatin nna dar gr 6 d 11 n usggʷasad i trfiqt n ifrdaw tiɣanimin nna ɣ llan 20 n iḍuṛan ilkm umḍan n imzdaɣn nns 997 n
Generated Text Samples (Subword-based)
Below are text samples generated from each subword-based Markov chain model:
Context Size 1:
_sgmawimda_tabiran_4422._uwafargn),_nartan_49_an
Context Size 2:
n_des_ig_twuṭṭa_u_n_10.09_n_uḍwwaṛ_tɛṛanbattamaslmd
Context Size 3:
_n_umḍan_d_imir_an_tamatay_n_i_tugt_n_tznit_taru_260_n
Context Size 4:
_n_umzdaɣn_tasga_n_t_n_ayt_baha_ɣ_lli__n_iɣ_isggʷasn_d_tr
Key Findings
- Best Predictability: Context-4 (word) with 95.2% predictability
- Branching Factor: Decreases with context size (more deterministic)
- Memory Trade-off: Larger contexts require more storage (207,789 contexts)
- Recommendation: Context-3 or Context-4 for text generation
4. Vocabulary Analysis
Statistics
| Metric | Value |
|---|---|
| Vocabulary Size | 31,623 |
| Total Tokens | 2,378,986 |
| Mean Frequency | 75.23 |
| Median Frequency | 4 |
| Frequency Std Dev | 1969.53 |
Most Common Words
| Rank | Word | Frequency |
|---|---|---|
| 1 | n | 294,723 |
| 2 | ɣ | 102,005 |
| 3 | d | 64,397 |
| 4 | s | 35,003 |
| 5 | nna | 34,361 |
| 6 | imzdaɣn | 31,398 |
| 7 | dar | 30,865 |
| 8 | gr | 30,722 |
| 9 | tgmiḍi | 30,050 |
| 10 | usggʷas | 28,210 |
Least Common Words (from vocabulary)
| Rank | Word | Frequency |
|---|---|---|
| 1 | tdarwinit | 2 |
| 2 | talmuqqdimt | 2 |
| 3 | ttawnn | 2 |
| 4 | taggrgist | 2 |
| 5 | umdgar | 2 |
| 6 | uqṛiḍ | 2 |
| 7 | dearborn | 2 |
| 8 | ghosts | 2 |
| 9 | tremblay | 2 |
| 10 | tmmndl | 2 |
Zipf's Law Analysis
| Metric | Value |
|---|---|
| Zipf Coefficient | 1.2850 |
| R² (Goodness of Fit) | 0.988028 |
| Adherence Quality | excellent |
Coverage Analysis
| Top N Words | Coverage |
|---|---|
| Top 100 | 69.6% |
| Top 1,000 | 90.6% |
| Top 5,000 | 95.5% |
| Top 10,000 | 97.3% |
Key Findings
- Zipf Compliance: R²=0.9880 indicates excellent adherence to Zipf's law
- High Frequency Dominance: Top 100 words cover 69.6% of corpus
- Long Tail: 21,623 words needed for remaining 2.7% coverage
5. Word Embeddings Evaluation
5.1 Cross-Lingual Alignment
5.2 Model Comparison
| Model | Dimension | Isotropy | Semantic Density | Alignment R@1 | Alignment R@10 |
|---|---|---|---|---|---|
| mono_32d | 32 | 0.6948 | 0.3782 | N/A | N/A |
| mono_64d | 64 | 0.5226 | 0.3533 | N/A | N/A |
| mono_128d | 128 | 0.2352 | 0.3437 | N/A | N/A |
| aligned_32d | 32 | 0.6948 🏆 | 0.3868 | 0.0060 | 0.0540 |
| aligned_64d | 64 | 0.5226 | 0.3472 | 0.0240 | 0.1280 |
| aligned_128d | 128 | 0.2352 | 0.3345 | 0.0360 | 0.1780 |
Key Findings
- Best Isotropy: aligned_32d with 0.6948 (more uniform distribution)
- Semantic Density: Average pairwise similarity of 0.3573. Lower values indicate better semantic separation.
- Alignment Quality: Aligned models achieve up to 3.6% R@1 in cross-lingual retrieval.
- Recommendation: 128d aligned for best cross-lingual performance
6. Morphological Analysis (Experimental)
This section presents an automated morphological analysis derived from the statistical divergence between word-level and subword-level models. By analyzing where subword predictability spikes and where word-level coverage fails, we can infer linguistic structures without supervised data.
6.1 Productivity & Complexity
| Metric | Value | Interpretation | Recommendation |
|---|---|---|---|
| Productivity Index | 5.000 | High morphological productivity | Reliable analysis |
| Idiomaticity Gap | -0.041 | Low formulaic content | - |
6.2 Affix Inventory (Productive Units)
These are the most productive prefixes and suffixes identified by sampling the vocabulary for global substitutability patterns. A unit is considered an affix if stripping it leaves a valid stem that appears in other contexts.
Productive Prefixes
| Prefix | Examples |
|---|---|
-t |
tmurrant, taɣwwaɣt, tuwuri |
-i |
ill, itturray, iɛisayn |
-ta |
taɣwwaɣt, tagnsant, tabrruct |
-a |
anmmassu, asaki, atayn |
-u |
umzizwr, uɣnja, umdlu |
-l |
lmuddn, lmɣrib, lbadiɛ |
-ti |
timqqit, tisutam, tinglizt |
-m |
mggrn, mennawt, magẓnt |
Productive Suffixes
| Suffix | Examples |
|---|---|
-n |
atayn, mggrn, krnun |
-t |
tmurrant, priest, taɣwwaɣt |
-a |
uɣnja, phoenicia, iɣrruba |
-in |
ɛalawiyyin, bdrnin, irwin |
-s |
ghosts, yuns, palmas |
-i |
asaki, bani, tuwuri |
-e |
became, institute, neige |
-an |
dan, ubrkan, uljmɛan |
6.3 Bound Stems (Lexical Roots)
Bound stems are high-frequency subword units that are semantically cohesive but rarely appear as standalone words. These often correspond to the 'core' of a word that requires inflection or derivation to be valid.
| Stem | Cohesion | Substitutability | Examples |
|---|---|---|---|
adda |
1.68x | 52 contexts | addan, hadda, wadda |
ggar |
1.97x | 22 contexts | uggar, ggarn, iggar |
ggʷa |
1.62x | 43 contexts | ḥggʷa, aggʷa, zggʷar |
ugga |
1.91x | 21 contexts | uggar, uggan, tugga |
wuri |
1.70x | 30 contexts | twuri, tuwuri, twwuri |
tion |
2.05x | 14 contexts | nation, notion, action |
matt |
1.64x | 26 contexts | matta, nmatti, amattu |
lati |
1.61x | 27 contexts | latif, latin, talati |
ɣrib |
1.76x | 20 contexts | aɣrib, mɣrib, lmɣrib |
mɣri |
1.77x | 13 contexts | tmɣri, imɣri, mɣrib |
ddad |
1.62x | 14 contexts | ḥddad, addad, addadn |
mata |
1.54x | 14 contexts | smata, amata, umata |
6.4 Affix Compatibility (Co-occurrence)
This table shows which prefixes and suffixes most frequently co-occur on the same stems, revealing the 'stacking' rules of the language's morphology.
| Prefix | Suffix | Frequency | Examples |
|---|---|---|---|
-t |
-t |
636 words | takrrayt, tusnaktant |
-i |
-n |
489 words | ittajjan, igatn |
-t |
-n |
323 words | tunisian, tmttawin |
-t |
-in |
264 words | tmttawin, tmdinin |
-l |
-a |
101 words | lqliɛa, lɛmaṛa |
-t |
-a |
71 words | tggʷra, tawayya |
-i |
-an |
60 words | ittajjan, ixxan |
-a |
-n |
60 words | aẓuran, ayncṭayn |
-l |
-t |
39 words | lmɛiṭat, luṭilat |
-a |
-an |
39 words | aẓuran, alilan |
6.5 Recursive Morpheme Segmentation
Using Recursive Hierarchical Substitutability, we decompose complex words into their constituent morphemes. This approach handles nested affixes (e.g., prefix-prefix-root-suffix).
| Word | Suggested Split | Confidence | Stem |
|---|---|---|---|
| magrebini | magreb-in-i |
7.5 | in |
| mzaraynin | mzaray-n-in |
7.5 | n |
| imaynutnin | imaynut-n-in |
7.5 | n |
| tiɣrmanin | tiɣrm-an-in |
7.5 | an |
| ikkattinn | ikkatt-in-n |
7.5 | in |
| tisntutin | tisntu-t-in |
7.5 | t |
| tasnmḍant | tasnmḍ-an-t |
7.5 | an |
| tuɣnijinin | tuɣnij-in-in |
7.5 | in |
| ittyawnna | ittyaw-n-na |
7.5 | n |
| tinidlisn | t-in-idlisn |
7.5 | idlisn |
| fransisku | fransis-k-u |
7.5 | k |
| gibraltar | gibral-t-ar |
7.5 | t |
| iblḥsanin | iblḥsa-n-in |
7.5 | n |
| ittyurnan | ittyur-n-an |
7.5 | n |
| africaines | africa-in-es |
7.5 | in |
6.6 Linguistic Interpretation
Automated Insight: The language Tachelhit shows high morphological productivity. The subword models are significantly more efficient than word models, suggesting a rich system of affixation or compounding.
7. Summary & Recommendations
Production Recommendations
| Component | Recommended | Rationale |
|---|---|---|
| Tokenizer | 64k BPE | Best compression (3.82x) |
| N-gram | 2-gram | Lowest perplexity (255) |
| Markov | Context-4 | Highest predictability (95.2%) |
| Embeddings | 100d | Balanced semantic capture and isotropy |
Appendix: Metrics Glossary & Interpretation Guide
This section provides definitions, intuitions, and guidance for interpreting the metrics used throughout this report.
Tokenizer Metrics
Compression Ratio
Definition: The ratio of characters to tokens (chars/token). Measures how efficiently the tokenizer represents text.
Intuition: Higher compression means fewer tokens needed to represent the same text, reducing sequence lengths for downstream models. A 3x compression means ~3 characters per token on average.
What to seek: Higher is generally better for efficiency, but extremely high compression may indicate overly aggressive merging that loses morphological information.
Average Token Length (Fertility)
Definition: Mean number of characters per token produced by the tokenizer.
Intuition: Reflects the granularity of tokenization. Longer tokens capture more context but may struggle with rare words; shorter tokens are more flexible but increase sequence length.
What to seek: Balance between 2-5 characters for most languages. Arabic/morphologically-rich languages may benefit from slightly longer tokens.
Unknown Token Rate (OOV Rate)
Definition: Percentage of tokens that map to the unknown/UNK token, indicating words the tokenizer cannot represent.
Intuition: Lower OOV means better vocabulary coverage. High OOV indicates the tokenizer encounters many unseen character sequences.
What to seek: Below 1% is excellent; below 5% is acceptable. BPE tokenizers typically achieve very low OOV due to subword fallback.
N-gram Model Metrics
Perplexity
Definition: Measures how "surprised" the model is by test data. Mathematically: 2^(cross-entropy). Lower values indicate better prediction.
Intuition: If perplexity is 100, the model is as uncertain as if choosing uniformly among 100 options at each step. A perplexity of 10 means effectively choosing among 10 equally likely options.
What to seek: Lower is better. Perplexity decreases with larger n-grams (more context). Values vary widely by language and corpus size.
Entropy
Definition: Average information content (in bits) needed to encode the next token given the context. Related to perplexity: perplexity = 2^entropy.
Intuition: High entropy means high uncertainty/randomness; low entropy means predictable patterns. Natural language typically has entropy between 1-4 bits per character.
What to seek: Lower entropy indicates more predictable text patterns. Entropy should decrease as n-gram size increases.
Coverage (Top-K)
Definition: Percentage of corpus occurrences explained by the top K most frequent n-grams.
Intuition: High coverage with few patterns indicates repetitive/formulaic text; low coverage suggests diverse vocabulary usage.
What to seek: Depends on use case. For language modeling, moderate coverage (40-60% with top-1000) is typical for natural text.
Markov Chain Metrics
Average Entropy
Definition: Mean entropy across all contexts, measuring average uncertainty in next-word prediction.
Intuition: Lower entropy means the model is more confident about what comes next. Context-1 has high entropy (many possible next words); Context-4 has low entropy (few likely continuations).
What to seek: Decreasing entropy with larger context sizes. Very low entropy (<0.1) indicates highly deterministic transitions.
Branching Factor
Definition: Average number of unique next tokens observed for each context.
Intuition: High branching = many possible continuations (flexible but uncertain); low branching = few options (predictable but potentially repetitive).
What to seek: Branching factor should decrease with context size. Values near 1.0 indicate nearly deterministic chains.
Predictability
Definition: Derived metric: (1 - normalized_entropy) × 100%. Indicates how deterministic the model's predictions are.
Intuition: 100% predictability means the next word is always certain; 0% means completely random. Real text falls between these extremes.
What to seek: Higher predictability for text generation quality, but too high (>98%) may produce repetitive output.
Vocabulary & Zipf's Law Metrics
Zipf's Coefficient
Definition: The slope of the log-log plot of word frequency vs. rank. Zipf's law predicts this should be approximately -1.
Intuition: A coefficient near -1 indicates the corpus follows natural language patterns where a few words are very common and most words are rare.
What to seek: Values between -0.8 and -1.2 indicate healthy natural language distribution. Deviations may suggest domain-specific or artificial text.
R² (Coefficient of Determination)
Definition: Measures how well the linear fit explains the frequency-rank relationship. Ranges from 0 to 1.
Intuition: R² near 1.0 means the data closely follows Zipf's law; lower values indicate deviation from expected word frequency patterns.
What to seek: R² > 0.95 is excellent; > 0.99 indicates near-perfect Zipf adherence typical of large natural corpora.
Vocabulary Coverage
Definition: Cumulative percentage of corpus tokens accounted for by the top N words.
Intuition: Shows how concentrated word usage is. If top-100 words cover 50% of text, the corpus relies heavily on common words.
What to seek: Top-100 covering 30-50% is typical. Higher coverage indicates more repetitive text; lower suggests richer vocabulary.
Word Embedding Metrics
Isotropy
Definition: Measures how uniformly distributed vectors are in the embedding space. Computed as the ratio of minimum to maximum singular values.
Intuition: High isotropy (near 1.0) means vectors spread evenly in all directions; low isotropy means vectors cluster in certain directions, reducing expressiveness.
What to seek: Higher isotropy generally indicates better-quality embeddings. Values > 0.1 are reasonable; > 0.3 is good. Lower-dimensional embeddings tend to have higher isotropy.
Average Norm
Definition: Mean magnitude (L2 norm) of word vectors in the embedding space.
Intuition: Indicates the typical "length" of vectors. Consistent norms suggest stable training; high variance may indicate some words are undertrained.
What to seek: Relatively consistent norms across models. The absolute value matters less than consistency (low std deviation).
Cosine Similarity
Definition: Measures angular similarity between vectors, ranging from -1 (opposite) to 1 (identical direction).
Intuition: Words with similar meanings should have high cosine similarity. This is the standard metric for semantic relatedness in embeddings.
What to seek: Semantically related words should score > 0.5; unrelated words should be near 0. Synonyms often score > 0.7.
t-SNE Visualization
Definition: t-Distributed Stochastic Neighbor Embedding - a dimensionality reduction technique that preserves local structure for visualization.
Intuition: Clusters in t-SNE plots indicate groups of semantically related words. Spread indicates vocabulary diversity; tight clusters suggest semantic coherence.
What to seek: Meaningful clusters (e.g., numbers together, verbs together). Avoid over-interpreting distances - t-SNE preserves local, not global, structure.
General Interpretation Guidelines
- Compare within model families: Metrics are most meaningful when comparing models of the same type (e.g., 8k vs 64k tokenizer).
- Consider trade-offs: Better performance on one metric often comes at the cost of another (e.g., compression vs. OOV rate).
- Context matters: Optimal values depend on downstream tasks. Text generation may prioritize different metrics than classification.
- Corpus influence: All metrics are influenced by corpus characteristics. Wikipedia text differs from social media or literature.
- Language-specific patterns: Morphologically rich languages (like Arabic) may show different optimal ranges than analytic languages.
Visualizations Index
| Visualization | Description |
|---|---|
| Tokenizer Compression | Compression ratios by vocabulary size |
| Tokenizer Fertility | Average token length by vocabulary |
| Tokenizer OOV | Unknown token rates |
| Tokenizer Total Tokens | Total tokens by vocabulary |
| N-gram Perplexity | Perplexity by n-gram size |
| N-gram Entropy | Entropy by n-gram size |
| N-gram Coverage | Top pattern coverage |
| N-gram Unique | Unique n-gram counts |
| Markov Entropy | Entropy by context size |
| Markov Branching | Branching factor by context |
| Markov Contexts | Unique context counts |
| Zipf's Law | Frequency-rank distribution with fit |
| Vocab Frequency | Word frequency distribution |
| Top 20 Words | Most frequent words |
| Vocab Coverage | Cumulative coverage curve |
| Embedding Isotropy | Vector space uniformity |
| Embedding Norms | Vector magnitude distribution |
| Embedding Similarity | Word similarity heatmap |
| Nearest Neighbors | Similar words for key terms |
| t-SNE Words | 2D word embedding visualization |
| t-SNE Sentences | 2D sentence embedding visualization |
| Position Encoding | Encoding method comparison |
| Model Sizes | Storage requirements |
| Performance Dashboard | Comprehensive performance overview |
Generated by Wikilangs Pipeline · 2026-03-02 12:00:43



















