HSC Pro flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Sufficiency test

A data statement is sufficient only when it produces exactly one possible value for the target quantity. Two or more valid values, or an unbounded range, means insufficient.

Two-part analysis rule

Both parts of the answer must be correct simultaneously. Eliminate any option pair in which either part fails, even when the other part is clearly supported by the data.

Inclusion-exclusion principle

For two sets, the union size equals the sum of the set sizes minus their intersection. For three sets, add singles, subtract pairwise overlaps, then add back the triple overlap.

Combined work rate

When two agents work in parallel, their rates add: 1/T = 1/a + 1/b. Opposing flows, such as filling and draining, subtract instead of adding.

Source conflict resolution

When two sources report different figures, compare their as-of dates, definitions, and scope. Prefer the primary raw dataset over a summary citing it.

Truncated axis distortion

A graph axis that does not start at zero exaggerates differences. Check axis origin and scale breaks before drawing any conclusion about relative magnitude.

Target quantity definition

State exactly what the question asks for before calculating. Intermediate results often appear as answer choices but respond to a different question than the one posed.

Sanity check by magnitude

Estimate the expected order of magnitude and units from the prompt. An answer that is off by a factor of ten or in the wrong unit is wrong regardless of arithmetic.

Successive percent change

Two consecutive changes multiply rather than add: the net effect is (1 + r1)(1 + r2) − 1. A 10% rise then 10% fall yields a 1% net decline.

Percentage points versus percent

A change from 20% to 25% is five percentage points but a 25% relative increase. Confusing the two overstates or understates the change depending on direction.

Weighted average formula

The combined mean equals the sum of each value times its weight, divided by the total weight. It always lies between the group means, closer to the larger group.

Rule of 70

At a constant growth rate of r percent per period, the doubling time is approximately 70 divided by r. Accurate for small rates; less so above roughly 15%.

Interquartile range outlier rule

A value is flagged as a potential outlier if it lies below Q1 minus 1.5 times the IQR, or above Q3 plus 1.5 times the IQR. Median and IQR resist outliers.

Correlation limits

The correlation coefficient ranges from minus one to plus one and measures only linear association. A strong correlation does not establish that one variable causes the other.

Base rate neglect

Even a highly accurate test produces many false positives when the condition is rare. The posterior probability depends on prevalence, not sensitivity alone.

Margin of error scaling

Margin of error shrinks roughly in proportion to one over the square root of sample size. Quadrupling the sample halves the margin; a biased sample stays biased.

Ratio to proportion conversion

A ratio a:b represents the fraction a divided by a plus b. Convert to proportions before comparing groups whose totals differ substantially.

Compound interest formula

Future value equals principal times one plus the rate divided by compounding periods, raised to the periods times years. More frequent compounding raises the effective annual rate.

Assumption negation test

To test a necessary assumption, negate the candidate statement. If the argument's conclusion collapses under that negation, the statement is a required assumption.

Strengthen and weaken targets

Effective answers attack or support the inferential link between evidence and conclusion. Restating the evidence more strongly rarely changes the argument's validity.

Dangling modifier error

A descriptive phrase must sit adjacent to the noun it modifies. Otherwise the sentence attributes the description to the wrong subject, creating an illogical statement.

Subject-verb agreement test

Delete intervening prepositional phrases to expose the true subject, then match the verb. Singular subjects take singular verbs regardless of nearby plural nouns.

Pronoun antecedent clarity

Every pronoun needs exactly one identifiable antecedent. The demonstrative this without a following noun is usually too vague for professional writing.

Logical comparison parallelism

Comparisons must place like categories against like categories: rates with rates, totals with totals, and one time period with a comparable period.

Parallel reasoning structure match

Match the argument's logical form, including conditional direction, quantifier strength, and scope. Shared topic or tone is irrelevant to structural equivalence.

Boldface statement roles

Classify each highlighted claim as premise, intermediate conclusion, or main conclusion. The role depends on what the claim supports, not on its position.

Recommendation-first structure

State the recommendation before its justification, keep one idea per sentence, and prefer active voice. Readers in professional settings scan for the decision first.

Ethical priority ordering

Resolve dilemmas in this order: safety of people, legal and regulatory compliance, organizational policy, then operational efficiency. Lower priorities never override higher ones.

Conflict of interest handling

Disclose the interest and then withdraw from the decision. Disclosure alone does not neutralize a material personal interest in the outcome.

Confidentiality exceptions

Confidentiality may be breached only under a specific documented exception: imminent risk of serious harm, legal compulsion, or authorized consent from the person concerned.

Competence boundary duty

Work outside your qualification must be declined, referred, or supervised by someone competent. Proceeding without disclosure breaches the duty of care to the client.

Escalation ladder

Raise the concern with the direct supervisor, then the designated compliance or ethics channel, then the external regulator if the matter remains unresolved internally.

Contemporaneous documentation

Record facts, dates, advice received, and actions taken at the time they occur. Label opinion as opinion and keep the record factual, complete, and retrievable.