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  0.0021  0.0378 -0.0029  0.0043 -0.0022
## X2  0.0021  1.0000 -0.0019  0.0000  0.0009  0.0001
## X3  0.0378 -0.0019  1.0000  0.0000  0.0032 -0.0014
## X4 -0.0029  0.0000  0.0000  1.0000 -0.0014 -0.0017
## X5  0.0043  0.0009  0.0032 -0.0014  1.0000  0.0018
## X6 -0.0022  0.0001 -0.0014 -0.0017  0.0018  1.0000
names(Xsum) <- M1:M2
Xsum %>%
  summary %>%
  round(2) 
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    2.70   16.37   20.37   21.03   24.97   66.45
Xsum %>%
  sd %>%
  round(2)
## [1] 6.49
Xsum %>%
  `<=`(5) %>%
  which %>%
  `[`(Xsum, .) %>%
  round(2)
## 5002489 5007327 5032170 5050920 5057826 5073995 5075061 5083869 5087448 5094229 
##    4.93    3.72    4.91    4.77    4.87    4.89    3.84    4.66    4.55    3.92 
## 5102577 5106150 5107983 5116635 5130560 5134043 5154159 5163828 5165025 5171952 
##    4.69    4.76    4.51    4.58    3.22    4.96    4.31    4.89    3.40    4.07 
## 5199626 5211423 5212939 5214592 5215367 5227596 5227878 5230181 5230935 5237583 
##    4.87    4.81    4.75    4.10    4.34    4.85    4.95    3.56    3.04    3.78 
## 5238853 5250998 5258341 5262385 5263830 5267350 5275695 5276022 5278595 5283114 
##    4.13    3.55    4.66    3.94    4.27    4.79    4.69    4.51    4.59    3.97 
## 5283278 5292338 5301015 5310579 5321465 5324201 5327310 5336016 5364563 5370443 
##    4.88    4.87    4.72    3.59    4.81    4.58    3.01    3.62    4.82    4.52 
## 5380640 5396542 5399595 5413277 5414867 5437989 5448304 5452222 5458288 5459491 
##    4.56    4.96    4.93    4.77    4.23    4.94    4.80    4.71    4.98    4.22 
## 5478131 5486974 5490165 5491754 5512539 5527093 5535510 5545635 5552963 5579348 
##    3.93    4.67    4.64    4.83    4.31    4.62    4.83    3.98    4.52    4.50 
## 5581245 5587191 5589199 5606128 5609550 5611650 5617906 5642196 5647148 5648486 
##    4.91    4.75    2.70    4.23    4.61    4.37    4.25    4.57    4.99    4.21 
## 5648885 5660207 5660968 5670675 5671336 5675929 5677919 5681890 5688935 5692120 
##    4.96    4.46    4.56    4.98    4.91    4.56    4.44    4.57    3.96    4.70 
## 5694538 5703418 5714387 5717598 5735642 5736719 5739325 5739463 5748250 5759481 
##    4.65    4.24    3.51    4.12    3.65    4.59    4.86    4.07    4.64    4.15 
## 5770232 5797695 5798600 5808406 5812932 5833813 5839213 5845994 5847327 5855811 
##    4.85    4.55    4.20    4.51    4.89    4.81    3.80    4.59    4.34    3.83 
## 5864610 5868492 5869349 5871368 5874288 5877964 5878493 5903978 5918295 5919458 
##    4.78    3.67    4.91    4.66    3.92    3.32    4.93    4.89    4.07    4.61 
## 5962121 5980763 5985885 5993284 
##    4.61    3.06    3.92    2.97
Xmin <- names(Xsum[which(Xsum == min(Xsum))])
Xmin
## [1] "5589199"

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] 1.2860187 0.1624764 0.0000000 0.0000000 0.9764732 0.2719614
## 
## $Xsum
## [1] 2.69693

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 20 29 26 50 20 51 112
Black 17 29 29 58 18 47 110
X1min <- tbl1 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X1min
## X-squared 
##  1.286019

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 147 161
Black 152 156
X2min <- tbl2 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X2min
## X-squared 
## 0.1624764

학적 상태

tbl3 <- class_roll$status %>%
  table(class_roll$group, .) 
tbl3 %>%
  pander
  학생 휴학
Red 278 30
Black 278 30
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 259 49
Black 259 49
X4min <- tbl4 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X4min
## X-squared 
##         0

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 23 30 34 26 27 35 27 36 38 32
Black 24 32 34 27 24 29 28 38 38 34
X5min <- tbl5 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X5min
## X-squared 
## 0.9764732

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 65 47 26 170
Black 63 48 23 174
X6min <- tbl6 %>%
  chisq.test(simulate.p.value = TRUE) %>%
  `[[`(1)
X6min
## X-squared 
## 0.2719614

Sum of Chi_Squares

Xsum_min <- X1min + X2min + X3min + X4min + X5min + X6min
Xsum_min
## X-squared 
##   2.69693