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
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
Read MoreMatrix 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/
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-
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)
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: