Data Analysis and Inference

Learning from STAT206.

The bad:

• Inductive, rather than deductive
• Errors
• Formulas appear from nowhere

The good:

• Useful

Concepts

• Data Type

Collecting Data The goal: Ensure your data is representative of the population.

Biased data: Systematic errors in data collection.

• Numeris
• Psychology

Example solution: Having a TA per question, so the aggregate grades are what a student deserves.

Measure of Central Tendency

1. Sample Mean, see Mean
2. Sample median, not affected by extreme values
3. Quantile

Measures of Dispersion and Symmetry

1. Rang = max - min
2. $IQR=Q_3-Q_1$, where IQR is the inter-quartile range
3. Variance (or Variance (or Standard Deviation)
4. Skewness - measures bias towards left or right side
5. Kurtosis - Measure of normality

Plotting

• Violin Plot
• Boxplot