Latihan Pertemuan 2

Penyajian dan Peringkasan Data

Data

data <- c(12, 15, 18, 20, 22, 24, 25, 27, 30, 60, 12, 12, 13, 13, 13, 13, 13, 19, 19, 20, 20, 22, 22, 22, 22, 22, 22, 24, 24, 24)

1. Membuat Tabel Frekuensi

# Karena data tunggal, frekuensi tiap nilai = 1
freq_table <- table(data)
freq_table

## data
## 12 13 15 18 19 20 22 24 25 27 30 60 
##  3  5  1  1  2  3  7  4  1  1  1  1

# Jika ingin dalam bentuk data frame:
freq_df <- as.data.frame(freq_table)
colnames(freq_df) <- c("Nilai", "Frekuensi")
freq_df

##    Nilai Frekuensi
## 1     12         3
## 2     13         5
## 3     15         1
## 4     18         1
## 5     19         2
## 6     20         3
## 7     22         7
## 8     24         4
## 9     25         1
## 10    27         1
## 11    30         1
## 12    60         1

2. Diagram Lingkaran (Pie Chart)

pie(freq_table,
    main = "Pie Chart Data",
    col = rainbow(length(freq_table)))

3. Diagram Batang (Bar Chart)

barplot(freq_table,
        main = "Bar Chart Data",
        xlab = "Nilai",
        ylab = "Frekuensi",
        col = "lightblue")

4. Histogram

hist(data,
     main = "Histogram Data",
     xlab = "Nilai",
     ylab = "Frekuensi",
     col = "lightgreen",
     breaks = 5)

. Boxplot

boxplot(data,
        main = "Boxplot Data",
        ylab = "Nilai",
        col = "orange")

. Peringkasan Penyajian Data a. Ukuran Pusat Data

1. Rata-rata (Mean)

mean(data)

## [1] 20.8

2. Median

median(data)

## [1] 21

3. Modus

modus <- function(x) {
  ux <- unique(x)
  ux[which.max(tabulate(match(x, ux)))]
}
modus(data)

## [1] 22

# Catatan: karena semua nilai muncul sekali, tidak ada modus tunggal.

2. Ukuran Penyebaran Data

1. Range (MaxMin)

range_data <- max(data) - min(data)
range_data

## [1] 48

2. Kuartil dan IQR

Q1 <- quantile(data, 0.25)
Q3 <- quantile(data, 0.75)
IQR_data <- Q3 - Q1

Q1

##  25% 
## 13.5

Q3

##  75% 
## 23.5

IQR_data

## 75% 
##  10

3. Ragam (Variance)

var(data)

## [1] 79.82069

4. Simpangan Baku (Standard Deviation)

sd(data)

## [1] 8.934243

) Ringkasan Statistik Lengkap (Opsional, cepat)

summary(data)

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    12.0    13.5    21.0    20.8    23.5    60.0

) Mengihtung Variance populasi dan sample

# Data
x <- c(5, 7, 9, 10, 14)

# Mean
mean(x)

## [1] 9

# Ragam populasi
var_pop <- sum((x - mean(x))^2) / length(x)
var_pop

## [1] 9.2

# Ragam sampel
var(x)

## [1] 11.5