Skip to main content
STATISTICS FORMULAE
MEASURES OF CENTRAL TENDENCY:


  1) Range = Highest Value – Lowest Value

  2) No. Of Class Intervals = 1+ 3.2 log N (Struge’s Rule)

  3) Class Width = Range / No. Of Class Intervals.

                                           OR

     Class Intervals = Range / Class Width

  4) Arithmetic Mean = ∑ ‫/ ݔ‬n,        OR       ∑݂‫ / ݔ‬N

                                      ొ
                                        ି	୔.େ.୊
                                L+ቈ             ቉×H
                  ୬ାଵ                 మ
                    ଶ                      ୊
  5) Median =           or


          Where: L = Lower limit of median class, PCF = Previous Cumulative
     Frequency, F= Frequency of the Median Class, & H= Width of the CI


              ‫+ܮ‬ቂ                 ቃ×ℎ
                        ௙ଵି௙଴
                    ଶሺ௙ଵሻି௙௢ି௙ଶ
  6) Mode =

           Where: Where: L = Lower limit of modal class, f1 = Highest
     Frequency in the Distribution, f0 = Preceding Frequency to the Highest
     Frequency in the Distribution, f2 = Succeeding Frequency to the Highest
     Frequency in the Distribution, & H= Width of the CI


                         ௡                          ୒
                          భ                             ౜
                        ∑                           ∑
  7) Harmonic Mean =                  or
                          ೣ                             ౮

                                   ∑ ௅௢௚	௫                            ∑ ௙௅௢௚	௫
  8) Geometric Mean =	‫݃݋݈݅ݐ݊ܣ‬                               ‫݃݋݈݅ݐ݊ܣ‬
                                       ௡                                   ே
                                                    or



PraveenKumar Keskar                                                    1
ಿ
                                                                                ௥ቀ ర ቁି௉.஼.ி
                     ‫ݎ‬ቀ          ቁ              ‫ݎ‬ቀ         ቁ              ݈+ቈ                  ቉×ℎ
                           ௡ାଵ                       ேାଵ
                            ସ                         ସ                               ி
  9) Quartiles =                        or                        or



                                 ݊+1                 ܰ+1
                            ‫ݎ‬ቀ       ቁ or       ‫ݎ‬ቀ       ቁ
                                  10                  10
  10)      Deciles =                                              or

             ಿ
           ௥ቀ ቁି௉.஼.ி
     ݈+ቈ     భబ
                            ቉×ℎ
                 ி



                                ‫ ݎ‬ቀ ଵ଴଴ ቁ                 ‫ ݎ‬ቀ ଵ଴଴ ቁ
                                     ௡ାଵ                       ேାଵ
  11)      Percentile =                         or                        or

                           ಿ
                     ௥ቀ       ቁି௉.஼.ி
           ݈+ቈ            భబబ
                             ி
                                        ቉×ℎ

MEASURES OF DISPERSION:


  12)      Range = Highest Value – Lowest Value
                                   ୌ୧୥୦ୣୱ୲	୚ୟ୪୳ୣ	–	୐୭୵ୣୱ୲	୚ୟ୪୳ୣ
                                   ୌ୧୥୦ୣୱ୲	୚ୟ୪୳ୣା	୐୭୵ୣୱ୲	୚ୟ୪୳ୣ
           Co-efficient of Range =




                                             ୕ଷିொଵ
                                               ଶ
  13)      Quartile Deviation =
                                             ୕ଷିொଵ
                                             ொଷାொଵ
           Co-efficient of Q.D =



                                             ഥ
                                        ∑ |௫ି௫|                      ഥ
                                                               ∑ ௙|௫ି௫|
                                              ௡             ே
  14)      Mean Deviation =                               or
                                             ெ௘௔௡	஽௘௩௜௔௧௜௢௡	௙௥௢௠	௠௘௔௡
                                                          ெ௘௔௡
           Co-efficient of MD =




PraveenKumar Keskar                                                                       2
Standard Deviation = ට                               ට
                                          ∑ሺ௫ି௫̅ ሻమ                ∑ ௙ሺ௫ି௫̅ ሻమ
                                             ௡                            ே
  15)                                                     or

                                                          OR


                                                 ∑x ଶ                           ∑ fx ଶ
                                ට   ∑ x2
                                           −ቀ nቁ               ට   ∑ fx2
                                                                           −ቀ        ቁ
                                      n                             ୒            ୒
                                                          or

                                      × 100
                                  ஢
                                  ത
                                  ୶
    Co-efficient of Variation =

PROBABILITY:

  16)     Additional Theorem = PሺA ⋃ Bሻ = PሺAሻ + PሺBሻ − PሺA ⋂ Bሻ




                                          P ቆBൗAቇ = 	
                                                      ୔ሺ୅ ⋂ ୆ሻ
                                                        ୔ሺ୅ሻ
  17)     Conditional Theorem =



                                                        ୔ሺ୅ሻ×୔ሺ୅
          Baye’s Theorem = P ൬Aൗ ൰ = 	
                                                  ൗ୉ ሻ
                                Eଵ
                                                    భ
  18)                                             ୅ൗ ሻ
                                       ∑ ୔ሺ୉భ ሻ×୔ሺ ୉
                                                                      భ


  19)     Binomial Distribution:


          Probability Mass Function (P.M.F) =            nେ౮	 × ሺpሻ୶ × ሺqሻ୬ି୶

          Where,    ‫ݔ‬   = 0, 1, 2 _ _ _ n, p+q = 1


  20)     Poison Distribution

                    ሺ௘ ష೘ ሻ×ሺ௠ሻೣ
                           ௫!
          P.M.F =

          Where, x = 0, 1, 2, 3 _ _ _ _ _ _ _ _       ∞

PraveenKumar Keskar                                                              3
௫ି௠
                                        ఙ
  21)   Normal Distribution =

        Where m = mean &           ߪ = Standard Deviation

CORRELATION:

  22)   Karl Pearson’s Coefficient of Correlation:
                             ௡ஊ௫௬ିሺஊ௫ሻሺஊ୷ሻ
                    ඥ௡ஊ௫ మష	 ሺஊ௫ሻమ ඥ௡ஊ୷మష	 ሺஊ୷ሻమ
               r=



  23)   Spearman’s Rank Correlation:

                            ଺ሺஊୈమ ሻ
               r = 1-   [௡ሺ௡ ିଵሻ]
                               మ        where D = R1 – R2


               If any rank is repeated then;

                            ଺ሺஊୈమ ା	େ.୊.ሻ
               r=1–     [     ௡ሺ௡మ ିଵሻ
                                            ]
                        ௠ሺ௠మ ିଵሻ
                              ଵଶ
               C.F. =

               Where, m = No. of times the rank is repeated

REGRESSION:

  24)   If X is dependent on Y=

                                  ത)
               (‫ = ) ̅ݔ- ݔ‬bxy (‫ݕ- ݕ‬
                             ఙ௫
                            ఙ௬
               bxy = r
  25)   If Y is dependent on X =

PraveenKumar Keskar                                           4
ത)
                  (y -	‫ = ݕ‬byx (‫) ̅ݔ- ݔ‬
                             ఙ௬
                             ఙ௫
                  byx = r
                           ௡ஊ୶୷ିሺஊ୶ሻሺஊ୷ሻ
                           ௡ሺஊ୶మ ሻ	ି	ሺஊ୶ሻమ
                  byx =
                           ௡ஊ୶୷ିሺஊ୶ሻሺஊ୷ሻ
                           ௡ሺஊ୷మ ሻି	ሺஊ୷ሻమ
                  bxy =

                  r = ඥܾ௫௬	 × ܾ௬௫

TIME SERIES

  26)     Method of Moving Averages
  27)     Method of Least Squares
                  a) Linear Equation:
                       y = a + bx
                                    ∑௬            ∑ ௫௬
                                    ௡             ∑ ௫మ
                       Where, a =        ;   b=

                  b) Quadratic Equation:
                       y = a + bx + cx2
                       Normal Equations are:
                       Σy = na + bΣx + cΣx2
                       Σxy = aΣx + bΣx2 + cΣx3
                       Σx2y = aΣx2 + bΣx3 + cΣx4

INDEX NUMBERS

  28)     Unweighted Simple Average:
        a) Unweighted Arithmetic Mean Index Numbers =
                  ஊ௉
                  ௡
          P01 =

PraveenKumar Keskar                                      5
b) Unweighted Geometric Mean Index Number =
                           ஊ୪୭୥୔
                               ௡
          P01 = Antilog    (       )


  29)     Unweighted Simple Aggregative Index Numbers =
                  ஊ୔భ
                  ஊ୔బ
          P01 =         × 100
  30)     Weighted Average Relative Index Numbers:
        a) Weighted Arithmetic Mean Index Number =
                  ஊ୛୔
                  ஊ୛
          P01 =

        b) Weighted Geometric Mean Index Number =

          P01 = Antilog    (ஊ୛୪୭୥୔)
                             ஊ୛
  31)     Weighted Aggregative Index Number =
        a) Laspeyre’s Price Index Number =
                  ஊ୔భ ୕బ
                  ஊ୔బ ୕బ
          P01 =            × 100
        b) Paasche’s Price Index Number =
                  ஊ୔భ ୕భ
                  ஊ୔బ ୕భ
          P01 =            × 100
        c) Marshall Edgeworth’s Price Index Number =
                  ஊ୔భ ୕బ ା	ஊ୔భ ୕భ
                  ஊ୔బ ୕బ ା	ஊ୔బ ୕భ
          P01 =                        × 100
        d) Fisher’s Price Index Number =

          P01 =   ඥP଴ଵ ሺLaspeyre′sሻ × P଴ଵ	 ሺPaasche′sሻ	

                  = ඨΣP1 Q0 ×	 ΣP1 Q1
                     ΣP Q      ΣP Q
                       0 0       0 1



PraveenKumar Keskar                                       6