Information Coding and Control

Information Coding and Control Objectives

• Objectives are to understand codification concepts, apply them to real-life scenarios, understand information control, and apply different control types to data within applications.

Content Overview

• Information coding includes definitions, characteristics/types, coding and standardization, controllable codes, and conducting coding operations.
• Information control includes definitions, types, when to start control, and setting up error messages.

Information Coding Definitions

• A code is an abbreviated name or representation of information, used to designate objects or concepts clearly and uniquely.
• Codification is the process of replacing information in its natural form with a clearer code adapted for the user's needs involving the name and value.
• A coding language is a coding technique using an alphabet, syntax, and semantics.
• The alphabet consists of characters, numbers, and symbols.
• Syntax refers to code construction and assembly rules.
• Semantics means the meaning of the code.

Lexicographic Power

• Lexicographic power (Lex-Power) is the formula to count the total number of distinct values generated by a code, using the formula:
  • Lex-Power = c^t
  • c = number of characters in the alphabet.
  • t = word length.
• A code with 4 alphabetical positions has a Lex-Power of 26^4; a code with 4 numerical positions has a Lex-Power of 10^4
• A code with 2 alphabetical and 4 numerical positions has a Lex-Power of 26^2 x 10^4.

Coding Objectives

• The objectives are to identify an individual within a set, save space and time, represent object properties, and allow form controls within the information.

Characteristics of Coding

• Must be unambiguous, adaptable, allow new value insertion/extension, be concise, and meaningful.

Coding Types

• Basic coding, includes sequential, sequential by range, and significant.
• Complex Coding includes articulated/juxtaposed and hierarchical.

Sequential Coding

• Assigns consecutive numbers to objects in a set.
• An example is a company coding employees in order of recruitment (001, 002,..., 112), with new recruits assigned subsequent codes.
• Advantages include being unambiguous, easy to implement, and expandable.
• Disadvantages include being impossible to insert and not meaningful.

Sequential Coding by Range

• Divides objects into categories, each with a code range, with codes generally sequential within each range.
• A library classifies books by category, such as technology (001-100), literature (101-200), medicine (201-300), and general culture (301-400).
• Advantages are it is unambiguous, simple to implement, permits insertion within range, and allows possible extension.
• Disadvantages include a sometimes difficult number of codes in a range, an unclear division of objects into categories, and impossible insertion if the item number coded exceeds the specified range.

Significant Coding (Mnemonic)

• This involves abbreviating an object's designation using a reduced set of characters evocative of the object.
• Types include "Consonant codes" (removing vowels - e.g., FACTURE to FCTR).
• Types include abbreviative codes (e.g., FACTURE to FACT).

Articulated or Juxtaposed Coding

• This assigns codes divided into independent zones (descriptors), each related to the coded element.
• A car registration plate is an example .
• Advantages: Unambiguous, insertion and extension possible, grouping based on a criterion, widely used, and controllable.
• Disadvantages: Codes too long to handle, descriptor saturation possible, and instability if a descriptor changes, the whole code will need to change.

Hierarchical Coding

• Used when there are inclusion relationships between sets.
• The code is divided into multiple levels representing sets of objects with zones representing increasingly specific subsets from left to right.
• Advantages include similar advantages as articulated coding and easy searching via hierarchical levels.
• Disadvantages include similar disadvantages as articulated coding.
• An example is a university room number, e.g., ROOMID=E35, building code.

Coding and Standardization

• Currency coding (ISO 4217:2015) is DZD for Algerian dinar, EUR for euro, and USD for the US dollar.
• Representation of date and time (ISO 8601:2004): YYYY-MM-DD for dates and HH:MM:SS for hours.

Controllable Codes

• These codes rarely have any apparent meaning; the risk of errors during the writing or copying process is high.
• Adding a control key is important.
• Methods include an arithmetic method « MODULO 10 » and method of the control letter « MODULO 23 ».

"MODULO 10" Arithmetic Method

• Each digit is multiplied by 2 or 1 from the left, depending on whether it is odd or even.
• The sum of the products is subtracted from the next higher ten.
• If the code is 3261, the key calculation is (3x2) + (2x1) + (6x2) + (1x1) = 21. 30 - 21 = 9. Therefore, the code will be: 32619 and 9 is the control key.

"MODULO 23" Control Letter Method

• The control key is the letter corresponding to the assigned rank.
• Code modulo 23 + 1
• For example: If Code = 1249, calculate 1249 Modulo 23 = 7. The code will be: 1249H
• The letters I, O, and S are not taken into account, in order to avoid confusion with the numbers 1, 0, and 5.

Conducting Coding Operations

• Study the codes' future use, define populations to be coded, retain stable properties, and note possible corresponding values.
• Study the number of objects to be coded and its anticipated growth.
• Determine if any existing codes for the objects under study, define the code for its subsequent usage with internal and external stakeholders, and thoroughly test before using it.

Information Control

• Information control is to verify that the information characteristics conforms to what it should be.
• Direct and indirect are the two types of controls.

Control Types: Direct Controls

• It involves checking a given information itself without checking other information in the system.
• Presence or absence, type, and alignment control are the main types.

Presence or Absence Control

• Involves verifying whether information exists where it should be.
• Adding a new student involves verifying that they do not already exist in the student file (absence).
• Before entering a student's exam grades, it is necessary to first verify that they exist (presence).

Type Control

• Type control is checking if the information type corresponds to what it should be.
• Checks that information is written in the appropriate class (alphabetic, numeric, etc.) according to its meaning.
• Postal codes are numeric, so code 16I90 is wrong (i instead of 1).

Alignment Control

• Alignment refers to information within an input or filling area.
• Numeric information is right-aligned, while text can be left-aligned.

Control Types: Indirect Controls

• Checking the conformity of information against other information consists in checking the conformity of one item of information with other items.
• Indirect control without calculation performed with comparison.
• Indirect control with calculation performed by recalculating the item value.

Indirect Controls without Calculation

• Internal consistency checks for the accuracy of one information part against other parts of the same information.
  • A date control for JJ/MM/AAAA means that if MM=2, then 0<JJ<30
• External consistency checks the conformity of information with other information.
  • An employee's personnel number is made up of their year of recruitment and a sequential number. If the year of recruitment is 2020, then the number is 20/117
• Plausibility checks, making sure the information is plausible, possible, and conceivable in terms of its meaning.
  • A Wrong date of birth of 15/15/2000, means it is a Wrong date
  • A Wrong postal code is 601909

Indirect Controls with Calculation

• Involves recalculating the value of the information to be checked.
  • Stock quantity = Quantity received - Quantity issued.

Control Execution Order

• A typical order of controls: presence, type, alignment, internal/external consistency.

When to Start Control

• Control execution starts after entering the field.

Error Messages

• They should be visible, specify what's missing/unsuitable, indicate actions to be taken, use appropriate vocabulary, and guide the user with an example of expected information.

Conclusion

• Codifying and controlling valuable information properly processing validity/accuracy of results.
• A well-structured coding and control system improves data reliability, reduces inconsistencies, and enhances overall operational efficiency.