Manufacturing Quality Control ANOVA

import matplotlib.pyplot as plt
import numpy as np
import scipy.stats as stats

np.random.seed(654)

# Defects per 1000 units by shift
morning = np.random.normal(12.5, 3.2, 90)
afternoon = np.random.normal(15.8, 4.1, 90)
night = np.random.normal(18.2, 5.5, 90)
weekend = np.random.normal(14.1, 3.8, 90)

F_stat, p_value = stats.f_oneway(morning, afternoon, night, weekend)

fig, ax = plt.subplots(figsize=(12, 7), facecolor='#0d1117')
ax.set_facecolor('#0d1117')

colors = ['#F5D327', '#F5B027', '#5314E6', '#27D3F5']

parts = ax.violinplot([morning, afternoon, night, weekend], 
                       positions=[1, 2, 3, 4], showmeans=True, showmedians=True, widths=0.7)

for i, pc in enumerate(parts['bodies']):
    pc.set_facecolor(colors[i])
    pc.set_alpha(0.75)
    pc.set_edgecolor('white')
    pc.set_linewidth(1)

parts['cmeans'].set_color('#F5276C')
parts['cmeans'].set_linewidth(2.5)
parts['cmedians'].set_color('white')
for partname in ['cbars', 'cmins', 'cmaxes']:
    parts[partname].set_color('#555555')

# Control limits - labels on left side
ucl = 25
lcl = 5
ax.axhline(y=ucl, color='#ef4444', linestyle='--', alpha=0.8, linewidth=2)
ax.axhline(y=lcl, color='#22c55e', linestyle='--', alpha=0.8, linewidth=2)
ax.text(0.55, ucl+0.5, 'UCL', fontsize=9, color='#ef4444', va='bottom', fontweight='bold')
ax.text(0.55, lcl-0.5, 'LCL', fontsize=9, color='#22c55e', va='top', fontweight='bold')

# Fill between control limits
ax.fill_between([0.5, 4.5], lcl, ucl, alpha=0.08, color='#22c55e')

labels = ['Morning\n(6AM-2PM)', 'Afternoon\n(2PM-10PM)', 'Night\n(10PM-6AM)', 'Weekend']

# Stats annotation - bottom right
stats_text = f"ANOVA: F={F_stat:.2f}, p={p_value:.4f}"
bbox = dict(boxstyle="round,pad=0.3", facecolor='#1a1a2e', edgecolor='#F5D327', lw=2)
ax.text(0.98, 0.02, stats_text, transform=ax.transAxes, fontsize=10, color='white',
        ha='right', va='bottom', fontfamily='monospace', bbox=bbox)

ax.set_xticks([1, 2, 3, 4])
ax.set_xticklabels(labels, fontsize=10, color='white')
ax.set_ylabel('Defects per 1000 Units', fontsize=12, color='white', fontweight='500')
ax.set_title('Production Quality by Shift\nSix Sigma Control Analysis', 
             fontsize=14, color='white', fontweight='bold', pad=15)

ax.tick_params(colors='#888888')
for spine in ax.spines.values():
    spine.set_color('#333333')
ax.set_xlim(0.4, 4.6)
ax.set_ylim(0, 35)
ax.yaxis.grid(True, color='#1a1a2e', linewidth=0.5)
ax.set_axisbelow(True)

plt.tight_layout()
plt.show()