Reference · GRE subject tests

The mistakes GRE subject-test questions are built to catch.

A wrong answer on a subject test is not noise. Somebody wrote it, and wrote it to be chosen by a particular piece of muddled thinking. This page names 84 of those mistakes and counts how often the wrong answers in our own GRE Physics, Mathematics, and Psychology question bank were written to catch each one.

Read this first: what these numbers are, and what they are not

This is a classification of authored intent. Every practice item in our three GRE subject-test banks records, for each wrong option it offers, the specific error that would lead a student to pick it. This page counts those records. When it says an error accounts for 1,673 wrong answers, it means 1,673 wrong answers in this bank were written to catch it. That is a fact about how the questions were written and about nothing else.

It is not measured student performance. Nothing here comes from watching anyone take a test. There is no study, no sample, no analytics behind these figures. We are not claiming that any of these mistakes is common among real candidates, that any share of test-takers makes it, or that it costs anyone points. Those would be different claims needing different evidence, and we do not have that evidence.

The counts describe this question bank. They are the shape of one prep provider's writing across 2,509 items — its habits, its coverage, and its blind spots included. A different bank written against the same syllabus would produce different numbers. Nothing here describes the real exams, their item pool, or their design. Keiko Study is independent of ETS, and this page carries no endorsement from ETS or any other exam owner.

It is not finished and it is not validated. The list of 84 errors is what we have needed so far to name every wrong answer we have written; a longer bank would need more names. Nobody outside Keiko Study has reviewed it, and it has not been checked against any external dataset. We publish it because a stable, named vocabulary for wrong answers is more useful shared than kept, and because something written down can be argued with.

How the taxonomy was built

Writing a multiple-choice question is mostly writing the wrong answers. A distractor that nobody would pick is wasted; a good one is the exact output of a specific misunderstanding, so that choosing it tells you something. Our authoring model makes that explicit. Each item carries a set of rules, and a rule ties one offered wrong answer to one named error from a fixed list. Where an option is filler that no real reasoning produces, it is deliberately left unnamed rather than given a label that would not be true.

Across the three GRE subject tests that is 2,509 items carrying 9,279 named causes, drawn from 84 distinct errors. Each of the 84 has a stable code you can cite, a plain-language description, and a mapping onto one of four broader categories. The page you are reading is generated from that model on every deploy: no figure on it is typed by hand, and adding a question to the bank changes the numbers here without anyone editing this page.

One name is chosen per wrong answer, not several. Real mistakes are not always so tidy — a student can misread a condition and then misapply a rule — but a single named cause is what the model can support honestly, so that is what it records.

The shape of the list

The interesting split is not between subjects. It is between the errors that belong to a subject and the errors that belong to reading a question at speed. Thirteen of the 84 names are used by all three subject tests; the rest appear in exactly one.

Named errors by scope, and the wrong answers in this bank written to catch them
Where the name is used	Named errors	Wrong answers
All three subject tests	13	5,307
GRE Physics only	18	788
GRE Math only	29	945
GRE Psychology only	24	2,239

Counted by names, the subject-specific errors dominate. Counted by wrong answers, the shared ones do — the thirteen cross-exam names account for 5,307 of the 9,279 named causes in the bank. Reaching for a neighbouring definition, dropping a stated condition, and running a relationship the wrong way are not physics problems or psychology problems. They are what goes wrong when somebody who does know the material answers too quickly.

Four categories, and why the split matters

Every named error maps onto one of four broader codes. The distribution is the single most useful thing on this page for anyone deciding how to spend study time.

The four categories, the named errors mapped to each, and the wrong answers written to catch them
Category	What it means	Named errors	Wrong answers
Concept gap`concept_gap`	The response conflicts with a concept or relationship the item directly tests.	55	4,910
Misread condition`misread_condition`	The response is consistent with overlooking or changing an explicit condition in the prompt.	6	1,733
Wrong method`wrong_method`	The response uses or selects an approach that cannot solve the stated task.	17	1,440
Calculation or execution error`calculation_execution`	The selected method is compatible with the task, but an algebraic, arithmetic, logical, unit, or sign step fails.	6	1,196

55 of the 84 names are conceptual — the student has the wrong idea about what something is or how it behaves. Only 6 are about executing a calculation. If you are deciding between drilling arithmetic accuracy and rebuilding the concepts underneath it, the questions themselves were mostly written for the second problem. That is a fact about the questions, not a measurement of your own error rate — but if you are choosing what to practise blind, it is the better bet.

The twenty most-written-for errors

Ranked by how many wrong answers in this bank were written to catch them. Again: this ranks our authoring, not anybody's mistakes.

The twenty named errors with the most wrong answers written to catch them, split by exam
Named error	Physics	Math	Psychology	Total
Reached for a neighbouring definition`named_definition_confused`	410	247	1,016	1,673
Dropped a condition the problem stated`stated_condition_ignored`	141	94	283	518
Used the relationship in the wrong direction`inverse_relation_used_forward`	259	55	127	441
Accepted an absolute where the real claim is qualified`absolute_claim_accepted`	—	—	360	360
Right method, wrong power`exponent_miscounted`	255	96	6	357
Substituted the wrong given`wrong_value_substituted`	127	165	46	338
Reported a different quantity than the one asked for`different_quantity_reported`	139	137	43	319
Treated the result as independent of the change`dependence_ignored`	220	4	60	284
Left a factor out of the formula`factor_dropped_from_formula`	142	133	4	279
Assigned the function to the wrong structure`structure_function_misassigned`	—	—	256	256
Combined the quantities with the wrong rule`combination_rule_misapplied`	149	75	14	238
Leaned on a quantity that does not enter`irrelevant_quantity_invoked`	97	40	101	238
Lost or flipped a sign`sign_dropped_or_flipped`	107	116	8	231
Applied the version of the rule that fits a different case`wrong_case_of_rule_applied`	157	52	8	217
Right setup, slipped in the arithmetic`arithmetic_slip`	211	—	—	211
Named a different school of psychology`school_of_thought_confused`	—	—	206	206
Checked only part of the defining test`defining_test_incomplete`	—	197	—	197
Swapped a construct with its partner term`paired_construct_swapped`	—	—	179	179
Stopped at an intermediate result`intermediate_result_reported`	71	97	6	174
Named a different research design`research_design_misidentified`	—	—	169	169

Errors that are not about the subject

These 13 names are used by items in all three subject tests. A physics item and a psychology item have almost nothing in common, so when the same name explains a wrong answer in both, the mistake is not really about physics or psychology. It is about how a question gets read, how a relationship gets carried, and what gets dropped under time pressure.

That is the part of this list a tutor can use across subjects, and the part a student can work on without knowing any more content than they already do.

Reached for a neighbouring definition

named_definition_confused

The chosen answer names a closely related term or quantity rather than the one this item defines.

Say what the neighbouring term means and how it differs from this one. If you cannot state the difference in a sentence, the definition is not learned yet — it is only familiar.

1,673 wrong answers written to catch it · concept gap

Dropped a condition the problem stated

stated_condition_ignored

The chosen answer would be right if an explicitly stated condition or given value were not there.

Restate every condition the prompt gives in your own words, then check the option you chose still obeys all of them. The conditions are usually what makes one plausible answer wrong.

518 wrong answers written to catch it · misread condition

Used the relationship in the wrong direction

inverse_relation_used_forward

The chosen answer moves the result the way a direct relationship would, when the governing relationship is inverse (or the reverse).

Write the relationship as a proportionality before you compute, and decide from it whether the answer should get larger or smaller. Direction is a separate decision from magnitude, so make it separately.

441 wrong answers written to catch it · wrong method

Right method, wrong power

exponent_miscounted

The setup is sound but the quantity was raised to the wrong power, so the answer is off by a factor of the base.

Recount the power on every factor you changed, then check the size of the answer against the size of the change. Doubling a length and getting twice the volume is a caught error.

357 wrong answers written to catch it · calculation or execution error

Substituted the wrong given

wrong_value_substituted

The method is right, but a different number or symbol from the prompt was put into it.

Label each given with the symbol it belongs to before substituting anything. Two numbers of similar size cannot swap places if each is written next to its own symbol.

338 wrong answers written to catch it · misread condition

Reported a different quantity than the one asked for

different_quantity_reported

A correctly computed quantity was submitted, but not the one the prompt requested.

Write down the quantity being asked for before you start work, and check your last line against it. A correct answer to a question nobody asked still scores zero.

319 wrong answers written to catch it · misread condition

Treated the result as independent of the change

dependence_ignored

The chosen answer keeps the quantity fixed even though the thing that changed does control it.

Ask what the changed quantity actually controls and follow that chain one link at a time. Concluding that nothing moves is a claim, and it needs the same checking as any other.

284 wrong answers written to catch it · concept gap

Left a factor out of the formula

factor_dropped_from_formula

One of the multiplying factors in the governing formula never made it into the calculation.

Rebuild the formula from its definition, or from a units check, instead of recalling it whole. A missing factor is invisible in recall and obvious in a derivation.

279 wrong answers written to catch it · calculation or execution error

Combined the quantities with the wrong rule

combination_rule_misapplied

The right ingredients were used, but they were added, multiplied, or averaged where a different combination rule applies.

Decide how the quantities combine — added, multiplied, averaged, added in quadrature — before you combine them. Having the right ingredients is not the same as having the right recipe.

238 wrong answers written to catch it · wrong method

Leaned on a quantity that does not enter

irrelevant_quantity_invoked

The chosen answer makes the result hinge on something that cancels out or never appears in the governing relationship.

List the quantities that genuinely enter the governing relationship, then cross off the ones that cancel or never appear. A number being given does not mean it is used.

238 wrong answers written to catch it · concept gap

Lost or flipped a sign

sign_dropped_or_flipped

The magnitude is right and the direction is not: a minus sign was dropped, added, or reversed.

Fix a sign convention at the start and re-derive the sign of the final answer from that convention rather than from the arithmetic that produced it.

231 wrong answers written to catch it · calculation or execution error

Applied the version of the rule that fits a different case

wrong_case_of_rule_applied

A real rule was used, but the one that belongs to a neighbouring situation rather than the one described here.

Name the case you are in — which regime, which symmetry, which hypothesis holds — and then pick the version of the rule written for that case.

217 wrong answers written to catch it · wrong method

Stopped at an intermediate result

intermediate_result_reported

The work was correct up to a partial quantity, which was then reported instead of finishing the requested step.

Reread the final sentence of the prompt after you finish, and confirm the number on your page is the one it asks for rather than the one you needed on the way there.

174 wrong answers written to catch it · misread condition

GRE Physics error guide

Explore the named subject-specific errors, explanations and practical next steps for GRE Physics. Counts describe authored distractors in this bank, not measured learner performance.

Read the GRE Physics guide Open study hub

GRE Math error guide

Explore the named subject-specific errors, explanations and practical next steps for GRE Math. Counts describe authored distractors in this bank, not measured learner performance.

Read the GRE Math guide Open study hub

GRE Psychology error guide

Explore the named subject-specific errors, explanations and practical next steps for GRE Psychology. Counts describe authored distractors in this bank, not measured learner performance.

Read the GRE Psychology guide Open study hub

The complete list

All 84 names with their stable codes, their category, and their counts. The codes do not change: if you cite one, it will still mean the same thing after the bank grows. Each name links to its description on this page or in its subject guide.

Every named error with its code, category, scope, and the wrong answers written to catch it
Code	Named error	Category	Used by	Wrong answers
named_definition_confused	Reached for a neighbouring definition	Concept gap	All three	1,673
stated_condition_ignored	Dropped a condition the problem stated	Misread condition	All three	518
inverse_relation_used_forward	Used the relationship in the wrong direction	Wrong method	All three	441
absolute_claim_accepted	Accepted an absolute where the real claim is qualified	Misread condition	GRE Psychology	360
exponent_miscounted	Right method, wrong power	Calculation or execution error	All three	357
wrong_value_substituted	Substituted the wrong given	Misread condition	All three	338
different_quantity_reported	Reported a different quantity than the one asked for	Misread condition	All three	319
dependence_ignored	Treated the result as independent of the change	Concept gap	All three	284
factor_dropped_from_formula	Left a factor out of the formula	Calculation or execution error	All three	279
structure_function_misassigned	Assigned the function to the wrong structure	Concept gap	GRE Psychology	256
combination_rule_misapplied	Combined the quantities with the wrong rule	Wrong method	All three	238
irrelevant_quantity_invoked	Leaned on a quantity that does not enter	Concept gap	All three	238
sign_dropped_or_flipped	Lost or flipped a sign	Calculation or execution error	All three	231
wrong_case_of_rule_applied	Applied the version of the rule that fits a different case	Wrong method	All three	217
arithmetic_slip	Right setup, slipped in the arithmetic	Calculation or execution error	GRE Physics	211
school_of_thought_confused	Named a different school of psychology	Concept gap	GRE Psychology	206
defining_test_incomplete	Checked only part of the defining test	Concept gap	GRE Math	197
paired_construct_swapped	Swapped a construct with its partner term	Concept gap	GRE Psychology	179
intermediate_result_reported	Stopped at an intermediate result	Misread condition	All three	174
research_design_misidentified	Named a different research design	Wrong method	GRE Psychology	169
power_law_exponent_dropped	Scaled by the factor instead of its power or root	Wrong method	GRE Physics	134
reliability_validity_confused	Confused reliability with validity	Concept gap	GRE Psychology	132
stronger_property_assumed	Justified it with a stronger property than holds	Concept gap	GRE Math	130
disorder_category_confused	Placed the condition in the wrong diagnostic category	Concept gap	GRE Psychology	122
limit_case_overextended	Pushed the effect past the limit the conditions reach	Concept gap	GRE Physics	109
statistic_misidentified	Named a different statistic	Concept gap	GRE Psychology	108
theorist_misattributed	Credited the work to the wrong researcher	Concept gap	GRE Psychology	99
reciprocal_reported	Reported the reciprocal of the quantity asked for	Calculation or execution error	GRE Physics	96
therapy_school_confused	Described a different school of therapy	Concept gap	GRE Psychology	90
developmental_stage_misassigned	Placed the milestone in the wrong developmental stage	Concept gap	GRE Psychology	85
available_states_miscounted	Counted the available states or modes with the wrong rule	Concept gap	GRE Physics	78
boundary_case_misclassified	Got the boundary case backwards	Concept gap	GRE Math	62
formula_variant_misremembered	Recalled a near-miss version of the standard formula	Concept gap	GRE Math	61
memory_system_misassigned	Named a different memory system	Concept gap	GRE Psychology	57
neurotransmitter_misassigned	Named the wrong neurotransmitter	Concept gap	GRE Psychology	57
logical_form_altered	Rearranged the quantifiers or the implication	Concept gap	GRE Math	46
correlation_read_as_cause	Read an association as a cause	Wrong method	GRE Psychology	45
sleep_stage_misassigned	Assigned the feature to the wrong sleep stage	Concept gap	GRE Psychology	41
stage_order_reversed	Put the stages in the wrong order	Concept gap	GRE Psychology	41
convergence_test_misapplied	Leaned on a test that decides nothing here	Wrong method	GRE Math	40
hormone_misassigned	Named the wrong hormone	Concept gap	GRE Psychology	39
memory_process_misassigned	Blamed the wrong step of the memory process	Concept gap	GRE Psychology	37
element_order_confused_with_group_order	Confused an element's order with the group's size	Concept gap	GRE Math	35
nervous_system_division_confused	Named a different division of the nervous system	Concept gap	GRE Psychology	34
conservation_law_violated	Chose an outcome a conservation law forbids	Concept gap	GRE Physics	33
invariance_property_misjudged	Misjudged what the change leaves fixed	Concept gap	GRE Math	31
derivative_rule_misapplied	Applied the wrong calculus rule	Wrong method	GRE Math	29
limit_taken_by_naive_substitution	Read the limit straight off the substitution	Wrong method	GRE Math	26
reinforcement_contingency_swapped	Swapped what the consequence adds or takes away	Concept gap	GRE Psychology	25
matrix_entries_misread	Took the numbers from the wrong positions	Misread condition	GRE Math	24
prime_power_condition_misapplied	Misapplied the prime-power test	Concept gap	GRE Math	24
unit_zero_divisor_confused	Confused invertible elements with zero divisors	Concept gap	GRE Math	24
normalization_step_omitted	Never divided by the normalising quantity	Calculation or execution error	GRE Math	22
operation_table_property_confused	Named a different algebraic axiom	Concept gap	GRE Math	20
second_law_direction_ignored	Let heat run the way the second law forbids	Concept gap	GRE Physics	20
treatment_indication_confused	Matched the treatment to the wrong condition	Concept gap	GRE Psychology	19
complex_polar_form_confused	Mixed up modulus and argument	Concept gap	GRE Math	18
galilean_addition_used	Added the speeds the way everyday velocities add	Wrong method	GRE Physics	18
integration_differentiation_swapped	Ran the operation in the opposite direction	Wrong method	GRE Math	18
symmetry_argument_missed	Missed the symmetry that settles the integral	Concept gap	GRE Math	18
trace_determinant_swapped	Swapped trace and determinant	Concept gap	GRE Math	18
countability_misjudged	Misjudged which set can be listed	Concept gap	GRE Math	17
permutation_used_for_combination	Counted ordered arrangements where order does not matter	Wrong method	GRE Math	16
vector_product_direction_confused	Pointed a vector product the wrong way	Concept gap	GRE Physics	16
chain_rule_factor_omitted	Skipped the derivative of the inside function	Wrong method	GRE Math	14
intensity_coded_by_spike_size	Read stimulus intensity off the size of the impulse	Concept gap	GRE Psychology	14
rank_nullity_dimension_confused	Put the wrong dimension into rank-nullity	Wrong method	GRE Math	14
autonomic_division_swapped	Swapped the sympathetic and parasympathetic divisions	Concept gap	GRE Psychology	12
conditioning_paradigm_confused	Mixed up the two kinds of conditioning	Concept gap	GRE Psychology	12
lattice_type_confused	Recalled the count for a different lattice	Concept gap	GRE Physics	11
mass_distribution_misjudged	Judged rotation by mass alone, not where the mass sits	Concept gap	GRE Physics	11
unaffected_quantity_treated_as_changing	Assumed something changed that the setup leaves fixed	Concept gap	GRE Physics	11
pointwise_uniform_convergence_confused	Confused pointwise with uniform convergence	Concept gap	GRE Math	10
absolute_conditional_convergence_confused	Confused absolute with conditional convergence	Concept gap	GRE Math	9
cross_product_angle_misused	Used the wrong angle factor in a vector force law	Wrong method	GRE Physics	9
propagation_aligned_with_field	Assumed the wave travels along one of its fields	Concept gap	GRE Physics	9
equilibrium_stability_reversed	Read the stability of the equilibrium backwards	Concept gap	GRE Math	8
rate_confused_with_value	Read the effect off the value instead of its rate of change	Concept gap	GRE Physics	8
series_parallel_swapped	Swapped the series and parallel rules	Wrong method	GRE Physics	8
path_dependence_misjudged	Misjudged whether the answer depends on the path	Concept gap	GRE Math	6
absolute_temperature_not_used	Used the Celsius reading where the law needs kelvin	Wrong method	GRE Physics	4
algebraic_geometric_multiplicity_confused	Confused algebraic with geometric multiplicity	Concept gap	GRE Math	4
growth_model_linearized	Treated compounding change as linear	Concept gap	GRE Math	4
intensity_confused_with_photon_energy	Treated brighter light as more energetic per photon	Concept gap	GRE Physics	2

Using this, and arguing with it

Tutors and advisors are welcome to use these names, quote the descriptions, and link to the codes; each code has a stable anchor and a linked description. If you reproduce the counts, say what they count — wrong answers written to catch an error in one provider's bank — so the number does not travel as a claim about test-takers. That misreading is the only way this page can do harm.

If a name is wrong, badly drawn, or missing, say so. The most likely faults are the ones we cannot see from inside: names that split a single real mistake into two, names that collapse two different mistakes into one, and gaps where our bank simply has not covered a topic well enough to need a name yet.

Everything on this page is derived from the model that drives our practice. If the list changes, this page changes with it, and the codes stay stable so an old citation still resolves.

How content here is written and checked All exam hubs

Report an issue with this page