Mathematical Economics
Mathematical Economics · OptimisationProfit Maximisation with Calculus: First and Second Order ConditionsSetting the derivative to zero finds a flat point. Flat points can be peaks or valleys. The second-order condition is what tells you which one you have...
Statistics
Statistics · InferencePaired vs Independent t-test: How to Tell Them ApartSame test name, completely different setups — and picking the wrong one throws away half your statistical power. Here’s the one question that decides it.You’ve got two...
Statistics
Statistics · DistributionsZ-Scores and the Normal Distribution: A Plain-English GuideThe 68–95–99.7 rule, what a z-score really measures, and how to answer “what percentage scored above 85?” without fear.The normal distribution —...
Statistics
Statistics · InferenceNull vs Alternative Hypothesis: How to Set Them Up CorrectlyGetting the hypotheses wrong dooms the whole test before you’ve calculated anything. Here are the rules, the direction question, and the mistakes that cost the most...
Statistics
Statistics · Sampling distributionsThe Central Limit Theorem, Explained Like You’re in a HurryThe most important idea in statistics, and the one students most often nod along to without getting. Here’s what it actually says — and why it makes...
Statistics
Statistics · RelationshipsCorrelation Is Not Causation: The Five Reasons WhyEveryone can recite the slogan. Almost nobody can list the actual reasons two things might correlate without one causing the other. Here are all five.“Correlation isn’t...
Mathematical Economics
Mathematical Economics · CalculusMarginal Analysis: Why Every “Marginal” Concept Is a DerivativeMarginal cost, marginal revenue, marginal utility, marginal product. Four names, one piece of mathematics. Once you see it, half of economics becomes the...
Statistics
Statistics · Inferencet-test vs z-test: Which One Do You Actually Use?One question decides it, and almost everyone overcomplicates the answer. Here’s the rule, why the t-distribution exists at all, and the flowchart you can keep.You’re staring at an...
Statistics
Treatment A beats Treatment B in every single subgroup of patients — and yet, combine all the subgroups together, and Treatment B wins overall. This isn’t a contradiction or a calculation error. It’s a real, well-documented phenomenon called...
Statistics
A lottery ticket, an insurance policy, and a casino game all share the same underlying question: on average, across many repetitions, what should you expect to happen? The Statistics Made Simple Complete Bundle builds this idea up from first principles, with the same...
