Data

Search for Best Configuration

M1 <- 5000001
M2 <- 6000000
Xsum <- numeric(0)
Values_mat <- numeric(0)
for(k in M1:M2){
  set.seed(k)
  N <- nrow(class_roll) 
  class_roll$group <- 
    sample(1:N) %%
    2 %>%
    factor(levels = c(0, 1), labels = c("Red", "Black"))
  Xsum <- c(Xsum, red_and_black(class_roll)$Xsum)
  Values_mat <- rbind(Values_mat, red_and_black(class_roll)$Values)
}
colnames(Values_mat) <- paste0("X", 1:6)
# Values_mat
# pairs(Values_mat)
cor(Values_mat) %>%
  round(4)
##         X1      X2      X3      X4      X5      X6
## X1  1.0000 -0.0032  0.0224  0.0059 -0.0022 -0.0051
## X2 -0.0032  1.0000 -0.0015  0.0003 -0.0019  0.0009
## X3  0.0224 -0.0015  1.0000  0.0023 -0.0010 -0.0025
## X4  0.0059  0.0003  0.0023  1.0000 -0.0053  0.0001
## X5 -0.0022 -0.0019 -0.0010 -0.0053  1.0000 -0.0031
## X6 -0.0051  0.0009 -0.0025  0.0001 -0.0031  1.0000
names(Xsum) <- M1:M2
Xsum %>%
  summary %>%
  round(2) 
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    2.71   16.43   20.41   21.05   24.98   67.07
Xsum %>%
  sd %>%
  round(2)
## [1] 6.42
Xsum %>%
  `<=`(5) %>%
  which %>%
  `[`(Xsum, .) %>%
  round(2)
## 5011576 5037273 5063115 5064038 5074816 5077650 5083730 5087856 5100280 5122628 
##    4.42    4.30    4.87    4.33    4.71    4.95    2.79    4.92    4.00    4.44 
## 5124221 5139086 5152454 5156974 5176753 5186737 5189986 5202359 5230726 5236986 
##    3.21    4.97    4.91    4.50    4.26    4.85    4.92    4.68    4.11    4.61 
## 5274098 5274327 5274858 5283657 5290823 5303067 5308945 5310984 5311647 5314410 
##    4.46    4.84    4.66    4.01    4.90    4.25    4.23    4.47    4.87    4.77 
## 5365530 5367387 5369331 5383984 5396115 5406897 5408008 5414223 5416011 5417095 
##    4.90    4.55    4.41    4.79    3.89    4.39    5.00    4.47    4.27    4.66 
## 5451476 5469939 5484694 5491760 5492691 5496751 5508032 5527298 5532763 5534199 
##    4.58    4.43    4.77    2.71    3.17    4.29    4.63    4.87    4.76    3.99 
## 5534893 5536556 5544441 5545237 5549723 5550746 5560027 5570141 5572691 5598840 
##    4.75    4.96    4.17    4.45    4.75    4.97    4.87    4.70    4.90    4.54 
## 5602314 5607299 5628476 5631010 5645961 5666044 5669711 5675696 5676639 5689882 
##    4.82    4.89    4.80    4.06    4.91    4.66    4.86    4.70    2.93    3.78 
## 5740020 5743567 5757873 5763610 5765313 5765898 5766471 5768338 5770145 5784696 
##    4.68    4.94    4.03    4.45    4.82    4.15    3.69    4.78    3.76    4.53 
## 5791963 5807404 5814089 5818845 5833509 5835605 5844144 5871202 5876049 5877785 
##    4.50    4.67    4.32    4.96    3.96    3.21    4.77    3.38    4.93    2.88 
## 5878270 5889026 5894836 5911615 5918296 5920598 5923304 5932507 5943597 5945238 
##    3.01    4.37    4.42    3.59    4.89    4.93    4.95    4.49    4.24    4.95 
## 5955197 5959282 5961361 5972648 5977559 5981053 5985968 5986086 
##    4.54    3.98    4.68    4.80    4.78    4.83    3.81    4.78
Xmin <- names(Xsum[which(Xsum == min(Xsum))])
Xmin
## [1] "5491760"

Plot

hist(Xsum, prob = TRUE, nclass = 30, xlim = c(0, 50), ylim = c(0, 0.065))
x <- seq(0, 50, by = 0.1)
lines(x, dchisq(x, df = 21), col = "red")
legend("topright", inset = 0.05, legend = c("Xsum", "Chi-square(21)"), col = c("black", "red"), lty = 1)

plot(density(Xsum), xlim = c(0, 50), main = "Density Estimation of Xsum")
lines(x, dchisq(x, df = 21), col = "red")
legend("topright", inset = 0.05, legend = c("Xsum", "Chi-square(21)"), col = c("black", "red"), lty = 1)

Randomization

set.seed(Xmin)
N <- nrow(class_roll) 
class_roll$group <- 
  sample(1:N) %%
  2 %>%
  factor(levels = c(0, 1), labels = c("Red", "Black"))
red_and_black(class_roll)
## $Values
## [1] 1.75711392 0.07409415 0.00000000 0.14189781 0.29392569 0.44317627
## 
## $Xsum
## [1] 2.710208

학번

class_roll$id_2 <-
  class_roll$id %>%
  ifelse(. <= 2015, "2015", .)
tbl1 <- class_roll %$%
  table(.$group, .$id_2 %>% substr(1, 4)) %>%
  `colnames<-`(c("2015 이전", 2016:2021)) 
tbl1 %>%
  pander
  2015 이전 2016 2017 2018 2019 2020 2021
Red 17 35 30 33 17 68 43
Black 15 33 34 41 18 64 38
X1min <- tbl1 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X1min
## X-squared 
##  1.757114

학번 홀짝

tbl2 <- class_roll$id %>%
  as.numeric %>%
  `%%`(2) %>%
  factor(levels = c(1, 0), labels = c("홀", "짝")) %>%
  table(class_roll$group, .) 
tbl2 %>%
  pander
 
Red 121 122
Black 118 125
X2min <- tbl2 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X2min
##  X-squared 
## 0.07409415

학적 상태

tbl3 <- class_roll$status %>%
  table(class_roll$group, .) 
tbl3 %>%
  pander
  학생 휴학
Red 239 4
Black 239 4
X3min <- tbl3 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X3min
## X-squared 
##         0

e-mail 서비스업체

tbl4 <- class_roll$email %>%
  strsplit("@", fixed = TRUE) %>%
  sapply("[", 2) %>%
  `==`("naver.com") %>%
  ifelse("네이버", "기타서비스") %>%
  factor(levels = c("네이버", "기타서비스")) %>%
  table(class_roll$group, .) 
tbl4 %>%
  pander
  네이버 기타서비스
Red 204 39
Black 207 36
X4min <- tbl4 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X4min
## X-squared 
## 0.1418978

전화번호의 분포

cut_label <- paste(paste0(0:9, "000"), paste0(0:9, "999"), 
                   sep = "~")
tbl5 <- class_roll$cell_no %>%
  substr(start = 8, stop = 11) %>%
  sapply(as.numeric) %>%
  cut(labels = cut_label, 
      breaks = seq(0, 10000, by = 1000)) %>%
  table(class_roll$group, .) 
tbl5 %>%
  pander
  0000~0999 1000~1999 2000~2999 3000~3999 4000~4999 5000~5999 6000~6999 7000~7999 8000~8999 9000~9999
Red 20 22 22 27 30 23 21 29 24 25
Black 21 21 23 26 29 21 21 29 25 27
X5min <- tbl5 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X5min
## X-squared 
## 0.2939257

성씨 분포

f_name <- class_roll$name %>%
  substring(first = 1, last = 1) 
tbl6 <- f_name %>%
  `%in%`(c("김", "이", "박")) %>%
  ifelse(f_name, "기타") %>%
  factor(levels = c("김", "이", "박", "기타")) %>%
  table(class_roll$group, .) 
tbl6 %>%
  pander
  기타
Red 48 43 15 137
Black 44 40 16 143
X6min <- tbl6 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X6min
## X-squared 
## 0.4431763

Sum of Chi_Squares

Xsum_min <- X1min + X2min + X3min + X4min + X5min + X6min
Xsum_min
## X-squared 
##  2.710208