STATISTICS FORMULAE
MEASURES OF CENTRAL TENDENCIES (MEAN, MEDIAN AND MODE)
MEAN MEDIAN MODE UNGROUPED DATA ARITHMETIC MEAN (AM)
π₯ = Ξ£π₯π
GEOMETRIC MEAN (GM)
π₯ = π₯!. π₯!. π₯!β¦β¦ π₯!!
HARMONIC MEAN (HM)
π»π = π
Ξ£ 1 π₯ ππ
1π»π
= Ξ£ 1 π₯π
UNGROUPED DATA
ππππππ =π + 12
!!
ππ‘ππ
UNGROUPED DATA Most frequently occurring value
Or
ππππ = 3ππππππ β 2ππππ
GROUPED DATA ARITHMETIC MEAN (AM)
π₯ = Ξ£fπ₯π
GROUPED DATA
ππππππ = πΏ +π2 β πΉ ππ
GROUPED DATA
ππππ = πΏ +π!π
π! + π!
MEASURES OF DISPERSION / VARIABILITY
RANGE = π₯!"#$% !"#"$ β π₯!""#$ !"#"$
MEAN DEVIATION UNGROUPED DATA:
ππππ πππ£πππ‘πππ = Ξ£ π₯ β π₯
π
GROUPED DATA:
ππππ πππ£πππ‘πππ = Ξ£f π₯ β π₯
Ξ£π
STANDARD DEVIATION UNGROUPED DATA:
ππ‘ππππππ πππ£πππ‘πππ (π ππ π) = Ξ£ π₯ β π₯ !
n
GROUPED DATA:
ππ‘ππππππ πππ£πππ‘πππ (π ππ π) = Ξ£π π₯ β π₯ !
Ξ£π
INTER-ΒβQUARTILE RANGE = 25th percentile β 75th percentile
CO-ΒβEFFICIENT OF VARIATION:
πΆπ = SDMean
π 100 ππ ππ₯π100
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