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🇵🇰 NTS NAT-IGS · flashcards
NTS NAT-IGS Statistics Flashcards
59 question-and-answer cards covering Statistics as it is examined in NTS NAT-IGS. 24 of them are printed below, taken from across the deck — no signup, no paywall on the preview.
24 sample cards from the Statistics deck
Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.
Define the median.
The median is the middle value of an ordered data set that divides it into two equal halves; 50% of values lie below and 50% above it.
How do you find the median position for n ordered values?
The median is the value at position (n + 1)/2 when data is arranged in order; for even n it is the average of the two middle values.
Define the mode.
The mode is the value or category that occurs most frequently in a data set.
What is the empirical relationship between mean, median, and mode?
Mode = 3 Median − 2 Mean (for a moderately skewed distribution).
Which measure of central tendency is best for open-ended classes and why?
The median, because it depends only on the middle position and is not affected by extreme or undefined (open-ended) class limits.
Which average is most affected by extreme values?
The arithmetic mean is most affected by extreme values (outliers).
What is the formula for the geometric mean of n values?
Geometric Mean = ⁿ√(x₁ · x₂ · ... · xₙ), the nth root of the product of all n values; equivalently GM = antilog[(Σ log x)/n].
When is the geometric mean most appropriate?
The geometric mean is best for averaging ratios, rates of change, percentages, and growth rates (e.g., population or price index growth).
What is the formula for the harmonic mean of n values?
Harmonic Mean = n / Σ(1/x), the reciprocal of the arithmetic mean of the reciprocals of the values.
When is the harmonic mean most appropriate?
The harmonic mean is best for averaging rates and ratios such as speed (distance per time) when the units in the denominator are constant.
What is the relationship in size among the arithmetic, geometric, and harmonic means?
For positive values that are not all equal: AM ≥ GM ≥ HM (the arithmetic mean is largest and the harmonic mean is smallest).
What are quartiles?
Quartiles are three values (Q₁, Q₂, Q₃) that divide an ordered data set into four equal parts; Q₂ is the median.
What are deciles and percentiles?
Deciles are nine values (D₁–D₉) dividing ordered data into ten equal parts; percentiles are ninety-nine values (P₁–P₉₉) dividing it into one hundred equal parts.
What is the relationship between the median, Q₂, D₅, and P₅₀?
They are all equal — the median = second quartile (Q₂) = fifth decile (D₅) = fiftieth percentile (P₅₀).
What is the range and how is it calculated?
The range is the simplest measure of dispersion: Range = Largest value − Smallest value (Xmax − Xmin).
What is the quartile deviation (semi-interquartile range)?
Quartile Deviation = (Q₃ − Q₁) / 2; it measures the spread of the middle 50% of the data and ignores extreme values.
What is the interquartile range?
The interquartile range is the difference between the third and first quartiles: IQR = Q₃ − Q₁, covering the middle 50% of observations.
What is the mean deviation?
Mean deviation is the arithmetic mean of the absolute deviations of all values from a central value (usually the mean or median): MD = Σ|x − x̄| / n.
From which central value is the mean deviation the minimum?
The mean deviation is least (minimum) when deviations are measured from the median.
What is variance?
Variance is the average of the squared deviations of values from their mean: σ² = Σ(x − x̄)² / n.
What is the standard deviation and its formula?
Standard deviation is the positive square root of the variance: σ = √[Σ(x − x̄)² / n]. It measures the average spread of data about the mean.
Why is standard deviation often preferred over mean deviation?
Standard deviation uses squared deviations (avoiding the absolute-value problem), is algebraically tractable, and is used in further statistical analysis, making it the most reliable measure of dispersion.
What is the coefficient of variation and what does it measure?
Coefficient of Variation (CV) = (Standard Deviation / Mean) × 100. It is a relative, unit-free measure of dispersion used to compare variability between data sets; a lower CV indicates greater consistency.
What is the difference between population variance and sample variance formulas?
Population variance divides by N: σ² = Σ(x − μ)²/N, while sample variance divides by (n − 1): s² = Σ(x − x̄)²/(n − 1) to give an unbiased estimate.
What this deck covers
The Statistics deck follows the NTS NAT-IGS Statistics syllabus — 6 chapters and 20 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 9.8 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 124 characters, which is long enough to carry the reasoning and short enough to say out loud.
A deck like this earns its keep on the second and third pass. Read the syllabus first so you know the shape of the subject, then use the cards to find the specific facts that have not stuck.
Statistics flashcards FAQ
How many Statistics flashcards are in this NTS NAT-IGS deck?
59 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these NTS NAT-IGS flashcards free?
Yes. The preview here is free to read with no signup, and the full 59-card deck is free inside the Examius app.
What do the Statistics cards cover?
They follow the NTS NAT-IGS Statistics syllabus — 6 chapters and 20 topics — so the questions track what is actually examinable.
How should I use these flashcards?
Read the syllabus first so you know the shape of the subject, then drill the deck. Examius schedules each card with spaced repetition, so cards you keep missing come back sooner and ones you know drift further apart.