While the bussiness aid has an inclination on bussiness theories, the links are more scientific in nature.There are algorithms and quantitative methods used to back up and implement what the theory presents as important.You can choose a percentage and rate the sites you find here changing their sort order. If you know of a site with valuable and well presented science-inclined content you can e-mail me to include it on the links.
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algorithms

100% Kardi Teknomo's Tutorials on math and algorithm
80% Types of Neural Networks

algorithms for OfficeVBA

80% ReadyCode Downloads per math problem
75% Good source:Simple as well as Complex issues discussed
60% Good source:Simple as well as Complex issues discussed

business

85% A/B test significance calculator
85% Market Research: where marketing meets math
80% Circular economy indicators
80% Key Performance Indicators
50% Trust equation

economics

100% A valuable source(papers,theory,index databases)
60% Games on sustainability

finance

70% Finance tutorials
60% Excel tutorials

free courses

95% Greek University teachers made it on the e-course market
90% Stat Quest
90% Socratica code&math
85% Greekonomics Series
80% Complexity Explorer
70% Machine learning with SQL

game theory

90% The evolution of trust
90% Game Theory Tutorial and Virtual Lab
50% Game theory(history of)

math-statistics

100% Statistics Using Excel
100% statistics with excel(precise explanations)
85% Forecasting: Principles and Practice
85% Random Function Improvement - Aliases
85% Statistical Analysis Handbook
80% 3Blue1Brown
75% Linear Programming
70% about:education - simple explantions to common math problems
55% stats ang engineering handbook

statistics software

85% Statistics with @Risk
65% Statistics with VOSE