Fundamental of Statistics

Fundamental of Statistics

1. Definition

   • 1. Collection of quantitative data relating to a subject/group.
   • 2. Science dealing with the collection, tabulation, analysis, interpretation and presentation of quantitative data.

2. Phases

   • Descriptive - characteristics of a product/process using info. collected on it.
   • Inferential(Inductive) - draws conclusions on unknown process parameters based on info. contained in a sample.

3. Types of Data

   • Attribute
     • binary
     • qualitative data
     • Good/Bad
   • Variable
     • measurement info.
     • quantitative data
     • discrete vs. continuous

4. Describing Data

   • Graphical
     • Frequency Distribution
       • Categorical frequency distributions - nominal, ordinal level data
       • Ungrouped frequency distributions - small range
       • Grouped frequency distributions - large data
       • Histogram
   • Analytical
     • Measures of Central Tendency
       • Mode
     • Measures of Dispersion
       • Range = Max - Min

5. Relationship Between the Measures of Dispersion

   • ~ n increases = accuracy R decreases ~ small data = use R ~ smaller standard dev = better quality

6. Population vs Sample

   • Population - all items possessing characteristic of interest Sample - subsest of population

7. Parameter & Statistic

   • Parameter - describes a population Statistic - make inferences on population parameters

8. Normal Distribution

   • NORMAL = mean is best measure of central tendency

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