printer_data <- read.csv("C:/Users/hao/Desktop/BTL/XSTK/DATA XSTK/data.csv")
head(printer_data,3)
##   layer_height wall_thickness infill_density infill_pattern nozzle_temperature
## 1         0.02              8             90           grid                220
## 2         0.02              7             90      honeycomb                225
## 3         0.02              1             80           grid                230
##   bed_temperature print_speed material fan_speed roughness tension_strenght
## 1              60          40      abs         0        25               18
## 2              65          40      abs        25        32               16
## 3              70          40      abs        50        40                8
##   elongation
## 1        1.2
## 2        1.4
## 3        0.8
new_DF <- printer_data[,c("layer_height","wall_thickness","infill_density",
"infill_pattern","nozzle_temperature","bed_temperature","print_speed",
"material","fan_speed","tension_strenght","elongation")]
head(new_DF,3)
##   layer_height wall_thickness infill_density infill_pattern nozzle_temperature
## 1         0.02              8             90           grid                220
## 2         0.02              7             90      honeycomb                225
## 3         0.02              1             80           grid                230
##   bed_temperature print_speed material fan_speed tension_strenght elongation
## 1              60          40      abs         0               18        1.2
## 2              65          40      abs        25               16        1.4
## 3              70          40      abs        50                8        0.8
library(questionr)
freq.na(new_DF) #in kết quả dữ liệu bị khuyết
##                    missing %
## layer_height             0 0
## wall_thickness           0 0
## infill_density           0 0
## infill_pattern           0 0
## nozzle_temperature       0 0
## bed_temperature          0 0
## print_speed              0 0
## material                 0 0
## fan_speed                0 0
## tension_strenght         0 0
## elongation               0 0
new_function <- function(x){
  c(n=length(x),xtb=mean(x),sd=sd(x),Q1=quantile(x,probs=0.25),
  Q2=median(x),Q3=quantile(x,probs=0.75),min=min(x),max=max(x))
}

continous_data <- new_DF[,c("layer_height","wall_thickness","infill_density",
"nozzle_temperature","bed_temperature","print_speed","fan_speed","tension_strenght","elongation")]

apply(continous_data,2,new_function)
##        layer_height wall_thickness infill_density nozzle_temperature
## n       50.00000000      50.000000       50.00000           50.00000
## xtb      0.10600000       5.220000       53.40000          221.50000
## sd       0.06439673       2.922747       25.36348           14.82035
## Q1.25%   0.06000000       3.000000       40.00000          210.00000
## Q2       0.10000000       5.000000       50.00000          220.00000
## Q3.75%   0.15000000       7.000000       80.00000          230.00000
## min      0.02000000       1.000000       10.00000          200.00000
## max      0.20000000      10.000000       90.00000          250.00000
##        bed_temperature print_speed fan_speed tension_strenght elongation
## n            50.000000     50.0000  50.00000        50.000000 50.0000000
## xtb          70.000000     64.0000  50.00000        20.080000  1.6720000
## sd            7.142857     29.6923  35.71429         8.925634  0.7881883
## Q1.25%       65.000000     40.0000  25.00000        12.000000  1.1000000
## Q2           70.000000     60.0000  50.00000        19.000000  1.5500000
## Q3.75%       75.000000     60.0000  75.00000        27.000000  2.1750000
## min          60.000000     40.0000   0.00000         4.000000  0.4000000
## max          80.000000    120.0000 100.00000        37.000000  3.3000000
table(new_DF$infill_pattern)
## 
##      grid honeycomb 
##        25        25
table(new_DF$material)
## 
## abs pla 
##  25  25
hist(new_DF$tension_strenght,breaks=10,col="darkred",xlab="tension strenght",main="histogram tension strenght",xlim=c(0,40),ylim=c(0,15),labels=T)

boxplot(tension_strenght~infill_pattern,new_DF,col=c("red","blue"),
        main="tension_strenght and infill_pattern")

par(mfrow=c(2,4))

plot(new_DF$layer_height,new_DF$tension_strenght,xlab="layer_height",ylab="tension_strenght",main="layer height & tension strenght")

plot(new_DF$wall_thickness,new_DF$tension_strenght,xlab="wall_thickness",ylab="tension_strenght",main="wall_thickness & tension strenght")


plot(new_DF$infill_density,new_DF$tension_strenght,xlab="infill_density",ylab="tension_strenght",main="infill_density & tension strenght")

plot(new_DF$nozzle_temperature,new_DF$tension_strenght,xlab="nozzle_temperature",ylab="tension_strenght",main="nozzle_temperature & tension strenght")

plot(new_DF$bed_temperature,new_DF$tension_strenght,xlab="bed_temperature",ylab="tension_strenght",main="bed_temperature & tension strenght")

plot(new_DF$print_speed,new_DF$tension_strenght,xlab="print_speed",ylab="tension_strenght",main="print_speed & tension strenght")

plot(new_DF$fan_speed,new_DF$tension_strenght,xlab="fan_speed",ylab="tension_strenght",main="fan_speed & tension strenght")

plot(new_DF$elongation,new_DF$tension_strenght,xlab="elongation",ylab="tension_strenght",main="elongation & tension strenght")

library(corrplot)
## Warning: package 'corrplot' was built under R version 4.5.3
## corrplot 0.95 loaded
corrplot(cor(continous_data),method="number")

#bài toán 1 mẫu
n <- length(new_DF$tension_strenght)
xtb <- mean(new_DF$tension_strenght)
s <- sd(new_DF$tension_strenght)
data.frame(n,xtb,s)
##    n   xtb        s
## 1 50 20.08 8.925634
qqnorm(new_DF$tension_strenght)
qqline(new_DF$tension_strenght)

shapiro.test(new_DF$tension_strenght) 
## 
##  Shapiro-Wilk normality test
## 
## data:  new_DF$tension_strenght
## W = 0.9566, p-value = 0.06404
epsilon <- qt(p=0.05/2,df=n-1,lower.tail=FALSE)*s/sqrt(n)
print(epsilon)
## [1] 2.536637
data.frame(u1=xtb-epsilon,u2=xtb+epsilon)
##         u1       u2
## 1 17.54336 22.61664
#bài toán 2 mẫu KĐTB
abs_data <- subset(new_DF,material=="abs")
qqnorm(abs_data$tension_strenght)
qqline(abs_data$tension_strenght)

shapiro.test(abs_data$tension_strenght)
## 
##  Shapiro-Wilk normality test
## 
## data:  abs_data$tension_strenght
## W = 0.90604, p-value = 0.02489
pla_data <- subset(new_DF,material=="pla")
qqnorm(pla_data$tension_strenght)
qqline ( pla_data$tension_strenght)

shapiro.test(pla_data$tension_strenght)
## 
##  Shapiro-Wilk normality test
## 
## data:  pla_data$tension_strenght
## W = 0.92466, p-value = 0.06547
var.test(tension_strenght~material,new_DF,alternative="greater")
## 
##  F test to compare two variances
## 
## data:  tension_strenght by material
## F = 1.3045, num df = 24, denom df = 24, p-value = 0.26
## alternative hypothesis: true ratio of variances is greater than 1
## 95 percent confidence interval:
##  0.6575797       Inf
## sample estimates:
## ratio of variances 
##            1.30448
t.test(tension_strenght~material,new_DF,var.equal=T)
## 
##  Two Sample t-test
## 
## data:  tension_strenght by material
## t = -2.0972, df = 48, p-value = 0.04126
## alternative hypothesis: true difference in means between group abs and group pla is not equal to 0
## 95 percent confidence interval:
##  -10.028585  -0.211415
## sample estimates:
## mean in group abs mean in group pla 
##             17.52             22.64
#anova 1 nhân tố
new_DF$nozzle_temperature_2 <- ifelse(new_DF$nozzle_temperature < 220,"Group_1",
ifelse(new_DF$nozzle_temperature > 230 ,"Group_3","Group_2"))

Group_1 <- subset(new_DF,new_DF$nozzle_temperature_2=="Group_1")
Group_2 <- subset(new_DF,new_DF$nozzle_temperature_2=="Group_2")
Group_3 <- subset(new_DF,new_DF$nozzle_temperature_2=="Group_3")

qqnorm(Group_1$tension_strenght)
qqline(Group_1$tension_strenght)

shapiro.test(Group_1$tension_strenght)
## 
##  Shapiro-Wilk normality test
## 
## data:  Group_1$tension_strenght
## W = 0.91815, p-value = 0.09128
qqnorm(Group_2$tension_strenght)
qqline(Group_2$tension_strenght)

shapiro.test(Group_2$tension_strenght)
## 
##  Shapiro-Wilk normality test
## 
## data:  Group_2$tension_strenght
## W = 0.95684, p-value = 0.4829
qqnorm(Group_3$tension_strenght)
qqline(Group_3$tension_strenght)

shapiro.test(Group_3$tension_strenght)
## 
##  Shapiro-Wilk normality test
## 
## data:  Group_3$tension_strenght
## W = 0.87204, p-value = 0.1056
library(car)
## Warning: package 'car' was built under R version 4.5.3
## Loading required package: carData
## Warning: package 'carData' was built under R version 4.5.3
leveneTest(tension_strenght~as.factor(nozzle_temperature_2),data=new_DF)
## Levene's Test for Homogeneity of Variance (center = median)
##       Df F value Pr(>F)
## group  2  0.9575 0.3912
##       47
ANOVA_model<-aov(tension_strenght~as.factor(nozzle_temperature_2),data=new_DF)
summary(ANOVA_model)
##                                 Df Sum Sq Mean Sq F value Pr(>F)  
## as.factor(nozzle_temperature_2)  2    688   343.9   5.026 0.0105 *
## Residuals                       47   3216    68.4                 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
TukeyHSD(ANOVA_model)
##   Tukey multiple comparisons of means
##     95% family-wise confidence level
## 
## Fit: aov(formula = tension_strenght ~ as.factor(nozzle_temperature_2), data = new_DF)
## 
## $`as.factor(nozzle_temperature_2)`
##                   diff        lwr        upr     p adj
## Group_2-Group_1  -3.10  -9.430522  3.2305221 0.4678313
## Group_3-Group_1 -10.15 -17.903275 -2.3967255 0.0074607
## Group_3-Group_2  -7.05 -14.803275  0.7032745 0.0814970
plot(TukeyHSD(ANOVA_model))

model_1<-lm(tension_strenght~layer_height+wall_thickness+infill_density+infill_pattern
            +nozzle_temperature+bed_temperature+print_speed+material,data=new_DF)
summary(model_1)
## 
## Call:
## lm(formula = tension_strenght ~ layer_height + wall_thickness + 
##     infill_density + infill_pattern + nozzle_temperature + bed_temperature + 
##     print_speed + material, data = new_DF)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -9.4101 -3.8491  0.0338  3.9073 13.5086 
## 
## Coefficients:
##                          Estimate Std. Error t value Pr(>|t|)    
## (Intercept)             171.62809   54.21779   3.166  0.00292 ** 
## layer_height             55.59721   12.78771   4.348 8.87e-05 ***
## wall_thickness            1.06871    0.31942   3.346  0.00176 ** 
## infill_density            0.16286    0.03415   4.769 2.35e-05 ***
## infill_patternhoneycomb  -1.14271    1.64581  -0.694  0.49140    
## nozzle_temperature       -1.04681    0.36901  -2.837  0.00705 ** 
## bed_temperature           1.00534    0.47426   2.120  0.04012 *  
## print_speed              -0.01559    0.03006  -0.519  0.60679    
## materialpla             -17.30508    8.51530  -2.032  0.04864 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 5.58 on 41 degrees of freedom
## Multiple R-squared:  0.673,  Adjusted R-squared:  0.6092 
## F-statistic: 10.55 on 8 and 41 DF,  p-value: 6.91e-08
model_2<-lm(tension_strenght~layer_height+wall_thickness+infill_density+
              nozzle_temperature+bed_temperature+material,data=new_DF)
summary(model_2)
## 
## Call:
## lm(formula = tension_strenght ~ layer_height + wall_thickness + 
##     infill_density + nozzle_temperature + bed_temperature + material, 
##     data = new_DF)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -9.4717 -4.1695  0.0914  3.8586 13.9581 
## 
## Coefficients:
##                     Estimate Std. Error t value Pr(>|t|)    
## (Intercept)        167.02463   53.19880   3.140 0.003055 ** 
## layer_height        56.36695   12.44845   4.528 4.67e-05 ***
## wall_thickness       1.11169    0.28024   3.967 0.000271 ***
## infill_density       0.16643    0.03339   4.985 1.06e-05 ***
## nozzle_temperature  -1.02890    0.36321  -2.833 0.006996 ** 
## bed_temperature      0.98346    0.46685   2.107 0.041026 *  
## materialpla        -17.10365    8.39202  -2.038 0.047722 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 5.501 on 43 degrees of freedom
## Multiple R-squared:  0.6667, Adjusted R-squared:  0.6201 
## F-statistic: 14.33 on 6 and 43 DF,  p-value: 6.783e-09
par(mfrow=c(2,2))
plot(model_2)

shapiro.test(model_2$residuals)
## 
##  Shapiro-Wilk normality test
## 
## data:  model_2$residuals
## W = 0.97458, p-value = 0.3517
t.test(model_2$residuals)
## 
##  One Sample t-test
## 
## data:  model_2$residuals
## t = -7.5559e-16, df = 49, p-value = 1
## alternative hypothesis: true mean is not equal to 0
## 95 percent confidence interval:
##  -1.464546  1.464546
## sample estimates:
##     mean of x 
## -5.506598e-16
library(lmtest)
## Warning: package 'lmtest' was built under R version 4.5.3
## Loading required package: zoo
## Warning: package 'zoo' was built under R version 4.5.3
## 
## Attaching package: 'zoo'
## The following objects are masked from 'package:base':
## 
##     as.Date, as.Date.numeric
bptest(model_2)
## 
##  studentized Breusch-Pagan test
## 
## data:  model_2
## BP = 6.6773, df = 6, p-value = 0.3517
dwtest(model_2)
## 
##  Durbin-Watson test
## 
## data:  model_2
## DW = 1.5005, p-value = 0.01575
## alternative hypothesis: true autocorrelation is greater than 0

```