Tags: #◇CSMODEL #◇Mock Exams #◇Computer Science #◇Data Science #◇Statistical Modeling #◇Python #◇Machine Learning

---

Calculator Guide for CSMODEL Exam

This guide covers step-by-step instructions for calculating the most common formulas on a standard scientific calculator during the CSMODEL final exam.

◇1. Association Rule Mining (Apriori)

Formulas:

• Support(A) = Frequency(A) / Total Transactions
• Confidence(A → B) = Frequency(A and B) / Frequency(A)
• Lift(A → B) = Confidence(A → B) / Support(B) = Support(A and B) / [Support(A) * Support(B)]

Calculator Usage:

Calculating Lift:
Given: Confidence of A → B = 0.8, Support of B = 0.2

1. Type 0.8
2. Press / (divide)
3. Type 0.2
4. Press = (Result: 4.0)

◇2. Clustering (Euclidean Distance)

Formula:

• Distance = √[ (x₂ - x₁)² + (y₂ - y₁)² ]

Calculator Usage:

Given: Point 1 = (1, 2), Point 2 = (4, 6)
Method 1 (Step-by-step):

1. Calculate X difference: Type 4 - 1, press =, press the squaring key x² (Result: 9)
2. Add Y difference: Press +, open parenthesis (, type 6 - 2, close parenthesis ), press the squaring key x², press = (Result: 25)
3. Take the square root: Press the √ (square root) key, type 25 (or press Ans), then press = (Result: 5)

Method 2 (One-liner using parentheses):

1. Press √
2. Open parenthesis (
3. Open parenthesis (, type 4 - 1, close parenthesis ), press x²
4. Press +
5. Open parenthesis (, type 6 - 2, close parenthesis ), press x²
6. Close parenthesis )
7. Press = (Result: 5)

◇3. Recommender Systems (Cosine Similarity)

Formula:

• Cosine Similarity = (A · B) / (||A|| * ||B||)

Calculator Usage:

Given: Vector A = [3, 4], Vector B = [4, 3]

Step 1: Compute Dot Product (A · B)

1. Type 3 * 4
2. Press +
3. Type 4 * 3
4. Press = (Result: 24)
   (Write this number down: 24)

Step 2: Compute Magnitude of A (||A||)

1. Type 3² + 4², press = (Result: 25)
2. Press √ on the result (Result: 5)
   (Write this number down: 5)

Step 3: Compute Magnitude of B (||B||)

1. Type 4² + 3², press = (Result: 25)
2. Press √ on the result (Result: 5)
   (Write this number down: 5)

Step 4: Final Calculation

1. Type 24
2. Press /
3. Open parenthesis (
4. Type 5 * 5
5. Close parenthesis )
6. Press = (Result: 0.96)

◇4. Basic Statistics (Standard Error)

Formula:

• Standard Error (SE) = Standard Deviation / √(Sample Size)

Calculator Usage:

Given: Standard Deviation = 12, Sample Size = 36

1. Type 12
2. Press /
3. Press √ (square root), type 36
4. Press = (Result: 2.0)

◇5. Bayesian Inference (Bayes' Theorem)

Formula:

• P(A|B) = [ P(B|A) * P(A) ] / P(B)

Calculator Usage:

Given: P(B|A) = 0.9, P(A) = 0.01, P(B) = 0.05

1. Type 0.9 * 0.01
2. Press /
3. Type 0.05
4. Press = (Result: 0.18)

---

◇General Calculator Tips for the Exam:

• Parentheses are your best friend: When dealing with fractions (like Cosine Similarity or Bayes' theorem) with multiple terms in the denominator, always wrap the denominator in parentheses. A / (B * C) is NOT the same as A / B * C.
• Store intermediate values: For complex calculations like Cosine Similarity, write down the intermediate dot product and magnitudes on your scratch paper to avoid making a syntax error on a long one-line equation.
• Square Roots: Depending on your calculator (Casio vs. Sharp vs. TI), you either press √ before the number, or type the number and press √ after. Make sure you know which way your specific calculator works!
• Clear Memory: Hit AC or Clear twice before starting a completely new problem to ensure nothing is accidentally carried over from the previous calculation.

◇References & Navigation

• Related Notes: ◇Modeling and Simulation