R Programming and Machine Learning Essentials

What is R?

R is a free statistical software and programming language widely used by academics and professionals in statistics and data science.

Data Types in R

R stores data using different structures and types. Let’s start with data types:

  • Integer: Whole numbers (e.g., 3, 5, 7).
  • Double: Rational numbers with decimals (e.g., 8.2, 3.55).
  • Character: Text data (e.g., “Juan”, “Laura”).
  • Logical: Boolean values (TRUE or FALSE).

Data Structures in R

R uses various data structures to organize data:

  • Vectors
  • Factors
  • Lists
  • Data
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Inventory Management: Techniques and Costing Methods

Inventory Management

Inventories represent property for sale in the ordinary course of business. The range of functions and services of inventories depends on the nature and type of enterprise, the importance of the cost of materials and equipment, and the organization of the company. Inventory management focuses on four basic issues: the number of units to be produced in a given time, when inventory items deserve special attention, and how to protect against changes in inventory costs.

Inventory

Inventory

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Matrix Reduction and Diagonalization

ITEM 4: Determinants, Matrix Reduction, and Diagonalization

QR Factorization Theorem

If A is an m × n matrix with linearly independent columns, then A can be factored as A = QR, where Q is a matrix with orthonormal columns and R is an upper triangular matrix.

Example: Finding a QR Factorization

Find a QR factorization for the matrix A = [1 -2 1 / -1 3 2 / 1 1 -4].

Solution

By applying the Gram-Schmidt process to the columns of A, we get:

  • q1 = [1/√3, -1/√3, 1/√3]T
  • q2 = [0, 1/√2, 1/√2]T
  • q3 = [2/
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Setting Up an Auto Repair Shop: Essential Calculations

1. Market Study

New Building:

  • Sales of new vehicles by make, model.
  • Sales of used cars.
  • Cars in the workshop’s area of influence.
  • Number of similar workshops in the area.
  • Average size and turnover of local shops.

Transfer or Expansion:

  • Number of vehicles repaired per period.
  • Total hours billed per period.
  • Number of workers and their working hours.

2. Workload Calculation

New Building:

  • Number of fleet vehicles in the area (Pveh).
  • Market share (Mc).
  • Average time working on a vehicle (Hveh): Electromechanical (2-
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Understanding Statistical Concepts

Population and Elements

Population: All persons included in a study.

Elements: People or things within the population.

Variables

Variables: The focus of the study.

Quantitative Variables

Expressed in numeric values.

Discrete

Numerical values expressed in whole numbers (no decimals).

Continuous

Numerical values that can include decimals.

Attribute Variables

Values expressed in text.

Ordered

Have an accepted order.

Unordered

Do not have an order.

Data Sources

Primary Sources: First-hand information (interviews, surveys)

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Quantitative Data Collection and Analysis in Research

Quantitative Data Collection

Development and Implementation of Surveys

Obtaining data on both objective (factual) and subjective (opinions, attitudes) aspects based on information (oral and written) provided by the subject.

Creating Questionnaires

The basic tool for data collection in survey research, producing information through questioning.

Response Bias

  • Order Effects: A tendency to always choose the first or last response alternatives (e.g., assigning a rating on a scale of 1-7).
  • Acquiescence Bias:
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