Biostatistics — Flashcards

Flashcard 91: Formula for Mean for grouped data (where values are categorized): \(X_g\) = mid-point of each group \(f\) = frequency of each group Mean (\(\bar X\)) = _____

Answer: \(\frac{\sum (f \cdot X_g)}{n}\)

Flashcard 92: _____ was the founder of demography

Answer: Achille guillard

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Flashcard 93: The only method used to control for **unknown** confounders is:

Answer: Randomization

Extra: Randomization is the only method that can control for both **known and unknown** confounders by distributing them equally between study groups. **Methods to control confounding:** 1. **Design stage:** Randomization, Restriction, Matching. 2. **Analysis stage:** Stratification, Statistical modeling (Regression), Standardization. *RSSR is a mnemonic often used for: Randomization, Stratification, Standardization, Regression.* Reference: AIIMS Nov 2019

Flashcard 94: SE[standard error mean] formula(for quantitative data)

Answer: SD / √n

Extra: Standard Error of Mean (SEM) = Standard Deviation (SD) / √(Sample size (n))

Flashcard 95: observed Hb=18 g/dl mean Hb=14 g/dl standard deviation =2 g/dl z score=?

Answer: z score=2

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Flashcard 96: geometric mean is calculated in cases of _____

Answer: extreme values and exponential data

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Flashcard 97: Coefficient of variation (CV) is given by: _____

Answer: \(\frac{SD}{Mean} \times 100\%\)

Extra: The coefficient of variation (CV) is a statistical measure of the relative dispersion of data points in a data series around the mean. It is expressed as a percentage.

Flashcard 98: Formula for Median for grouped data, where Median group is where _____ lies \(L = \)_____ \(f_1 = \) _____ \(f_0 = \) _____ \(C_{f_0} = \) _____ \(i = group \ interval\) is given by _____

Answer: \(\frac {n}{2}^{th}\) observation

Extra: y

Flashcard 99: Some other measures of variability are: →Range = _____ →Coefficient of Range = _____ →Quartile Deviation = _____ →Coefficient of Quartile Deviation = _____ where, \(H\ =\ Highest\ Value\) \(L\ =\ Lowest\ Value\) \(Q_3 = 3(\frac {n+1}{4})^{th} observation\) \(Q_1 = (\frac {n+1}{4})^{th} observation\)

Answer: \(H-L\) 

Extra: y

Flashcard 100: c65872b736324b578b20a22eef5c027a-ao-6

Answer: tests of significance

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