Biostatistics Basics

Q: Which test compares means of MORE than two groups?

ANOVA. ANOVA compares means across >2 groups.

Q: Within ±2 SD of the mean lies about what % of a normal distribution?

95%. Approximately 95% of values fall within ±2 SD.

Q: The chi-square test is used for:

Categorical data. Chi-square analyses categorical/proportional data.

⭐ High-Yield Facts for Exam

Mean/median/mode = central tendency.
Median resists outliers.
±1/2/3 SD ≈ 68/95/99.7%.
Chi-square = categorical data.
t-test = 2 means; ANOVA = >2 means.

Measures of Central Tendency

Mean (average), median (middle value, robust to outliers), mode (most frequent).

Dispersion

Standard deviation (SD): in a normal distribution, ±1 SD ≈ 68%, ±2 SD ≈ 95%, ±3 SD ≈ 99.7% of values.

Tests of Significance

Chi-square — categorical/proportional data.
t-test — compare means of two groups.
ANOVA — compare means of more than two groups.
Correlation/regression for relationships.

Exam Tips ⭐

Median resists outliers; ±2 SD ≈ 95%; chi-square = categorical; t-test = 2 means; ANOVA = >2 means.

📝 Practice MCQs — Biostatistics Basics

Q1. Which test compares means of MORE than two groups?

A. t-test

B. Chi-square

C. ANOVA

D. Correlation

Show Answer

✅ Answer: C

ANOVA compares means across >2 groups.

Q2. Within ±2 SD of the mean lies about what % of a normal distribution?

A. 68%

B. 95%

C. 99.7%

D. 50%

Show Answer

✅ Answer: B

Approximately 95% of values fall within ±2 SD.

Q3. The chi-square test is used for:

A. Continuous means

B. Categorical data

C. Survival analysis

D. Correlation

Show Answer

✅ Answer: B

Chi-square analyses categorical/proportional data.

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⭐ High-Yield Facts for Exam