Wine Project Part A

Introduction

This report analyzes the red wine dataset from the UCI Machine Learning Repository. The goal is to explore data quality, outliers, summaries, distributions, and skewness.

1. Sample Size

The Red Wine dataset has 1599 samples with 11 physicochemical variables and 1 output variable (quality).

2. Data Quality Concerns

• Dataset does not have any missing values.
• All variables are numeric

3. Outliers

• Variables like residual sugar, total sulfur dioxide have extreme values compared to the rest of the data.
• Other variables like alcohol, pH, citric acid have fewer extreme points.

4. Summary Statisctics

• The statistics I have presented below for all variables are mean, standard deviation, min, max and median, which summarize the central tendency, spread and range of the data.

Summary Statistics for Red Wine

Variable	Mean	SD	Min	Max	Median
fixed.acidity	8.3196373	1.7410963	4.60000	15.90000	7.90000
volatile.acidity	0.5278205	0.1790597	0.12000	1.58000	0.52000
citric.acid	0.2709756	0.1948011	0.00000	1.00000	0.26000
residual.sugar	2.5388055	1.4099281	0.90000	15.50000	2.20000
chlorides	0.0874665	0.0470653	0.01200	0.61100	0.07900
free.sulfur.dioxide	15.8749218	10.4601570	1.00000	72.00000	14.00000
total.sulfur.dioxide	46.4677924	32.8953245	6.00000	289.00000	38.00000
density	0.9967467	0.0018873	0.99007	1.00369	0.99675
pH	3.3111132	0.1543865	2.74000	4.01000	3.31000
sulphates	0.6581488	0.1695070	0.33000	2.00000	0.62000
alcohol	10.4229831	1.0656676	8.40000	14.90000	10.20000
quality	5.6360225	0.8075694	3.00000	8.00000	6.00000

5. Distribution and Skewness

• Fixed Acidity: Most red wines have acidity around 7–8 with a few higher values. The distribution is slightly right-skewed.
• Volatile Acidity: Most values are around 0.3–0.6 with a few higher values, indicating a right-skewed distribution
• Citric Acid: Concentrated near 0, slightly right-skewed.
• Residual Sugar: Most wines have low sugar (1–3 g/L), but some have much more, creating a long tail on the higher end.
• Chlorides: Mostly low values, with a few high points. It is right-skewed distribution.
• Free Sulfur Dioxide: Most wines have low values, but some wines have higher amounts. Right-skewed distribution.
• Total Sulfur Dioxide: Similar to free sulfur dioxide but with a high range, distribution is right-skewed.
• Density: Most values are close to 0.995–0.998, distribution is even.
• pH: Most wines have pH around 3.2–3.5, distribution is almost even.
• Sulphates: Most wines have 0.5–0.7, with a few higher values.
• Alcohol: Most wines have 9–11% alcohol, distribution is fairly even with a few higher values.
• Quality: Most wines are rated 5 or 6, distribution is slightly skewed toward lower ratings.