LAFD FCA cheat sheet

Massed practice (one long block) produces fast gains but poor retention; spaced practice across days produces slower gains but durable recall.

Retrieval practice (recalling from memory) outperforms rereading by roughly 50-80% on delayed tests, even though rereading feels more productive.

Interleaving related topics forces discrimination between problem types and improves transfer to unfamiliar problems.

The forgetting curve is steepest in the first 24 hours; a review at 1 day, 1 week, and 1 month captures most of the retention benefit.

Working memory holds about 4 chunks; chunking raw data into meaningful groups (e.g., 911-555-0142 as three chunks) expands effective capacity.

Elaborative interrogation ('why is this true?') and self-explanation create more retrieval routes than verbatim memorization.

Feedback is most effective when immediate and specific to the error, not merely right/wrong.

Learning plateau is normal: performance often dips briefly during strategy change before improving.

Deductive validity: if premises are true and the form is valid, the conclusion must be true. Validity concerns form, not factual truth.

Modus ponens: P implies Q; P; therefore Q (valid). Modus tollens: P implies Q; not Q; therefore not P (valid).

Affirming the consequent (P implies Q; Q; therefore P) and denying the antecedent (P implies Q; not P; therefore not Q) are both invalid.

Correlation does not establish causation; alternative explanations include reverse causation, common cause, and selection bias.

Base-rate neglect: a 99% accurate test for a 1-in-10,000 condition yields mostly false positives - roughly 1 true positive per 100 positives.

Necessary condition: without it the outcome cannot occur. Sufficient condition: with it the outcome must occur. A condition can be one, both, or neither.

Analogical reasoning maps relations, not surface features; test an analogy by checking whether the shared relation holds in both cases.

Ordering and sequencing puzzles: draw a grid or timeline and mark exclusions first; constraints that eliminate options are more informative than those that allow them.

Main idea answers must cover the whole passage; an answer true only of one paragraph is a detail, not the main idea.

'EXCEPT' and 'NOT' questions invert the task: three options are supported, one is not - verify each against the text.

Inference answers must be forced by the text; if an option requires outside knowledge or a possible-but-unstated leap, it is wrong.

Tone and purpose questions hinge on evaluative words (e.g., 'unfortunately', 'remarkably') rather than on topic alone.

Audio dispatch order of information is typically location, nature of emergency, casualties, and unit requested; transcribe in that sequence.

In radio traffic, numbers and addresses are the highest-error elements; repeat back digits and street names to confirm.

Note-taking during audio should capture keywords and quantities, not full sentences - writing full sentences causes missed content.

When two speakers disagree, the answer often turns on who has direct observation versus secondhand report.

Order of operations: parentheses, exponents, multiplication/division left to right, addition/subtraction left to right.

Percent change = (new − old) / old × 100. A 20% increase followed by a 20% decrease yields a net 4% decrease, not zero.

Percent of a number: convert to decimal and multiply (15% of 240 = 0.15 × 240 = 36).

Ratios: to split a total T in ratio a:b, one share = T × a/(a+b).

Unit rates: distance = rate × time; rearrange as time = distance ÷ rate. Keep units consistent (minutes vs. hours).

Averages: mean = sum ÷ count. If a mean of n items is m, the total is n × m - useful for finding a missing value.

Fractions: to add, find a common denominator; to divide, multiply by the reciprocal (a/b ÷ c/d = a/b × d/c).

Rounding and estimation: round to compatible numbers to sanity-check an exact answer's magnitude before committing.

Strengthen an argument by removing an alternative explanation or supplying a needed assumption; weaken it by showing the evidence is compatible with the opposite conclusion.

An assumption is an unstated premise required for the conclusion; negate it - if the argument collapses, it was necessary.

Sample bias: conclusions about a population require a representative sample; self-selected or convenience samples typically overrepresent strong opinions.

Survivorship bias: data drawn only from successes omits the failures that would change the conclusion.

Absolute versus relative numbers: a doubling of a rare event can still be rare; check the base before judging magnitude.

Sufficient-versus-necessary errors occur when an argument treats one required factor as the only route to the outcome.

When a question asks for the conclusion, distinguish the claim being argued for from the evidence offered in support.

Translate word problems into an equation before computing: assign a variable to the unknown and write the relationship in symbols.

Work-rate problems: combined rate = sum of individual rates; time together = 1 ÷ (1/a + 1/b).

Weighted averages: total = sum of (group size × group average) divided by total count; never average two averages without weighting.

Percent increase then decrease: multiply factors (1.2 × 0.8 = 0.96), which is faster and safer than two separate calculations.

Proportion setup: cross-multiply a/b = c/d to get ad = bc; verify the units of both sides match.

Time arithmetic: convert to a single unit (minutes) before adding; 1 hour 45 minutes + 50 minutes = 155 minutes = 2 hours 35 minutes.

Check answers by substitution back into the original relationship, not by repeating the same arithmetic.

Procedural texts are usually ordered by sequence; signal words (first, before, until, after) define the required order.

Conditional instructions ('if X, then Y; otherwise Z') require checking the condition against the given facts before acting.

Negative instructions ('do not', 'except when') override general rules and are common distractors.

When a procedure contains a prerequisite, the prerequisite must be satisfied before the step, even if listed later.

Sequence questions: identify the step that must be first and the step that must be last; the remaining order usually follows from dependencies.

Quantities and thresholds in instructions (e.g., 'more than 10 minutes') are strict - 'more than' excludes exactly 10.

Summarizing a procedure in your own words exposes gaps in understanding faster than rereading it.