Survey sampling and estimation methods form the cornerstone of modern statistical inference, underpinning research across the social, medical, and natural sciences. At their heart, these methods ...

Adam Hayes, Ph.D., CFA, is a financial writer with 15+ years Wall Street experience as a derivatives trader. Besides his extensive derivative trading expertise, Adam is an expert in economics and ...

Primary research can be carried out in a number of different ways, for example surveys, questionnaires, focus groups or observations. A questionnaire is a set of questions to find out customers’ ...

Stratified sampling is used to select a sample that is representative of different groups. If the groups are of different sizes, the number of items selected from each group will be proportional to ...

Ever wonder how we collect our data? Today, most polls are conducted online. But, most pollsters reject the idea that “one size fits all” when it comes to polling, so we still use phone calls or mail ...

Abstract: In the dual three-phase permanent magnet synchronous motor (DTP-PMSM) drive, the loss of current information will lead to degradation of control performance. This paper proposes a resilient ...

Abstract: Various types of pressure sensors have been developed because pressure monitoring is essential in a variety of fields. Among these, optical methods have attracted attention due to their high ...

Will Kenton is an expert on the economy and investing laws and regulations. He previously held senior editorial roles at Investopedia and Kapitall Wire and holds a MA in Economics from The New School ...

Paper 1 Wed 3rd June 2026 2hrs, 100 marks Pure Maths 1 Paper 2 Thu 11th June 2026 2hrs, 100 marks Pure Maths 2 a-level-maths/ ├── README.md ← You are here ├── pure/ ← Pure Maths topics (Papers 1 & 2) ...