Statistika Deskriptif

Dr. Kusman Sadik, M.Si

Departemen Statistika IPB, 2018/2019

In discussing the methods for providing summary

descriptions of data, it helps to distinguish

between the two basic types:

1. Qualitative or categorical data

2. Quantitative or numerical or

measurement data

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(1) Discrete variable : the scale is made up of

distinct numbers with gaps in between

data count (number of bacteria, number of

ion, number of star, etc).

(2) Continuous variable : the measurement

scale does not have gaps, such variables are

called continuous height, weight, time.

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Frequency table

Pie chart

Bar chart / histogram

Pareto chart

Lihat Johnson , hlm. 25-29

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Distribution frequency table

Histogram

Dot diagram

Stem-and-Leaf (diagram dahan-daun)

Lihat Johnson , hlm. 29-36

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The graphic procedures help us to visualize the

pattern of a data set of measurements.

To obtain a more objective summary description

and a comparison of data sets, we must go one

step further and obtain numerical values for the

location or center of the data and the amount of

variability present.

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Rata-rata (mean)

Median

Kuartil

Persentil

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Kuartil dan Persentil

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Lihat Johnson , hlm. 40-4527

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Ragam (Variance)

Simpangan Baku (Standard Deviation)

Jangkauan (Range)

Jangkauan antar kuartil (Interquartile range)

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Lihat Johnson , hlm. 50-55

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Lihat Johnson (Example 17), hlm. 56

Min

Q1 Q2 Q3

Max

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Q1 = 4.4

Q2 = 9.4

Q3 = 17.5

(dari hasil sebelumnya)

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Apa interpretasi dari perbandingan 2 boxplot ini?

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Johnson (Exercise : 2.1), hlm. 36

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Johnson (Exercise : 2.17), hlm. 38

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Johnson (Exercise : 2.19), hlm. 38

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Johnson (Exercise : 2.22), hlm. 39

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Johnson (Exercise : 2.61), hlm. 57

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Johnson (Exercise : 2.67), hlm. 57

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Johnson (Exercise : 2.84), hlm. 59

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Johnson (Exercise : 2.89), hlm. 59

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Johnson, R.A. and Bhattacharyya, G.K. 2010.

Statistics, Principles and Methods 6th. John Wiley

& Sons, Inc., New York.

Montgomery, D.C. 2013. Design and Analysis of

Experiments 8th. John Wiley & Sons, Inc.,

Canada.

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