written by Rustam Fayzullayev

📌 Assessment

What is Statistics?

flowchart LR
    D["DATA"] --> C["Collecting<br>Analysing<br>Presenting"]
    C --> I["Making inferences<br>& conclusions"]

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Statistics is the science of collecting, analysing and presenting data in order to make inferences and draw conclusions.

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Rus: Статистика – наука о сборе, анализе и представлении данных для получения выводов.

📌 Statistics is used everywhere data is used to make decisions. Typical careers built on it: statistician, actuary, data analyst, data scientist, quantitative analyst ("quant"), biostatistician and risk manager.

Descriptive vs Inferential Statistics

flowchart TB
    S["Statistics"] --> D["DESCRIPTIVE"]
    S --> I["INFERENTIAL"]
    D --> D1["Organize"]
    D --> D2["Summarize"]
    D --> D3["Data presentation"]
    I --> I1["Generalize findings<br>from samples to populations"]
    I --> I2["Hypothesis testing"]
    I --> I3["Assess relationships<br>among variables"]
  1. Descriptive statistics – organizing, summarizing and presenting data, e.g. an average, a table or a chart
  2. Inferential statistics – using a sample to draw conclusions about a population, e.g. hypothesis testing
  3. Population – every member of the group we are interested in; its measures use Greek letters (μ, σ, N)
  4. Sample – the part of the population we actually observe; its measures use Latin letters (x̄, s, n)

Rus: Описательная статистика – упорядочение, обобщение и представление данных; статистический вывод (индуктивная статистика) – выводы о генеральной совокупности по выборке; генеральная совокупность; выборка.

📌 Example: which group is smarter? Two groups of 13 students took an IQ test.

Group IQ scores Mean
A 102 115 128 109 131 89 98 106 140 119 93 97 110 1,437 ÷ 13 = 110.54
B 127 162 131 103 96 111 80 109 93 87 120 105 109 1,433 ÷ 13 = 110.23