Saturday, December 5, 2015

Some Basic Stat Concepts from my notes

  • Correlation
    • Pearson: Product Corelation
    • Spearman: Rank Corelation
      • Whenever we have Ordinal Data (Rank Column, Marks of Students ).
      • If two ranks are same, then (next rank+(next+1))/2 rank, i:e (2+3)/2
      • If Three ranks are same, then rank is: (next rank+(next+1)+(next+2))/2. i: 1+3+4/2
      • And so on.
  • Hypothesis Test
    • Find t value
    • Find p value
    • Check it p value less than  or more than alpha
    • If p value is less than alpha then 
  • T Test: Sample Size is Small: Say 30.
    • One Tail Test
      • When Hypothesis talks about mean as > or < of Certail value
      • When Fail to reject Null Hypothesis?
        • If the P from test is > than Alpha(0.05, generally), then Null Hypothesis is Accepted(Failed to reject)
        • If T from experiment is < than T found out for Degree of Freedom(Number of Observations) and Critical Value (Alpha say 0.05) from T Table of One Tail, then Null Hypothesis is Accepted.
    • Two Tail Test
      • When Null Hypothesis talks about = of certain value.
      • When Fail to reject Null Hypothesis?
        • If the P from test is > than Alpha(0.05, generally), then Null Hypothesis is Accepted!(Failed to reject)
        • If T from experiment is beyond T Area(Experiment T must not fall in between Table T value range( found out for Degree of Freedom(Number of Observations) and Critical Value (Alpha say 0.05) from T Table of One Tail, then Null Hypothesis is Accepted.
  • Normal Distribution
    • 68-95-99.7 for 1,2,3 SD Area from Mean.
    • Standardization:
      • z(i)=(x-mean)/(standard distribution)
  • Skewness is a measure of symmetry, or more precisely, the lack of symmetry. A distribution, or data set, is symmetric if it looks the same to the left and right of the center point.
  • Kurtosisis a measure of whether the data are peaked or flat relative to a normal distribution.
  • Mean Absolute Deviation: x-Mean
  • Upper Hinge: Mid of Median to Max Value
  • Lower Hinge: Mid of Median to Min Value

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