User Guide – Z-Score

Overview

The Z-Score section in IdeasFarm allows objective and standardized evaluation of an animal's performance across multiple productive and health areas. It is based on statistical analysis of each indicator against the herd average, showing whether the animal is above, at, or below the average. The final result is a score (IFI – IdeasFarm Index) that helps make technical decisions regarding management, selection, and culling.

🔹 How to read the screen

1. Distribution Graph

• Center (0): represents the herd average.
• Positive values (+): the animal is above the average.
• Negative values (–): the animal is below the average.

This allows a quick visualization of the animal's strengths and weaknesses.

2. Evaluation Blocks

Each section groups specific indicators:

• Production: accumulated liters, lactation peak, days in milk, 305-day adjusted production, persistence, etc.
• Fertility: age at first service, days open, services per conception, calving interval.
• Reproductive health: abortions, stillbirths, difficult calvings.
• Body Condition (BCS): physical condition evaluated on a scale of 1 to 5.
• Management: adaptability, temperament, milking time.
• Health: diagnoses, treatments, and overall condition.
• Linear: morphological evaluation (pelvic angle, udder attachment, legs, etc.).

3. Indicators Table

Each table shows:

• IFI Index: calculated score for each characteristic.
• Animal Value: actual animal measurement.
• Herd Average: reference value.
• Difference: gap between the animal and the average.
• Z-Score: number of standard deviations from the mean.
• Normal CDF: statistical probability of that value occurring.
• Value per IFI point: the weight of each point in that indicator relative to the average.

Glossary of Statistical Concepts

• Z-Score: value indicating how many standard deviations the animal is from the average.
  • 0 = equal to the average.
  • Positive = better than the average.
  • Negative = worse than the average.
• Normal CDF: cumulative probability; translates the Z-Score to a range from 0 to 1 (e.g., 0.84 = the animal is better than 84% of the herd).
• IFI Index: IdeasFarm index that combines all weighted indicators to generate a single score.
• Value per IFI point: the contribution of each indicator point relative to the herd average.

📌 Usage Recommendations

• Interpret by blocks: the goal is not for an animal to excel in all areas, but to identify where it adds the most value.
• Use comparisons: review the difference against the herd average to detect improvement opportunities.
• Practical decisions:
  • Animals with high Z-Scores → maintain and optimize their management.
  • Animals with low Z-Scores and high costs → candidates for culling or management adjustment.
• Update records: the more complete the data (production, health, fertility), the more accurate the calculation.

👉 With this guide, users can easily understand and interpret Z-Scores, using the tool to support technical and economic decision-making.