Exploring Simple Random Samples
load("student_survey.RData")
random_sample = population[sample(length(population$Course),192),];random_sample
## Course Handed Sex Verbal Age
## 932 Natural left female 560 18.00
## 135 Natural right male 560 19.42
## 979 Business right female 400 18.17
## 821 Social right male 590 22.00
## 710 Social right female 730 19.58
## 993 Business left female 650 19.08
## 46 Social right female 660 18.00
## 1100 Business right female 540 18.67
## 1071 Business right male 550 19.08
## 260 Social right female 460 20.42
## 565 Social left female 550 19.58
## 281 Social right male 600 20.67
## 424 Natural right female 640 18.42
## 752 Social right female 660 20.00
## 1107 Business right female 570 20.25
## 533 Social right female 520 19.17
## 768 Social right female NA 19.83
## 403 Natural right male NA 20.75
## 244 Natural right male 750 19.58
## 726 Social right female NA 19.67
## 773 Social right male 530 25.42
## 878 Social right male NA 20.08
## 484 Natural right female 600 19.00
## 398 Natural right female 610 24.42
## 257 Social right female 690 18.42
## 612 Natural right female 510 20.33
## 833 Social right male 410 19.75
## 294 Social right male 540 29.75
## 1044 Social right male 640 23.75
## 488 Natural right male 560 19.00
## 886 Social right female 520 19.75
## 633 Natural right male 580 19.08
## 994 Business right female 660 18.67
## 154 Natural left male 580 22.00
## 373 Social left female 570 20.92
## 460 Natural left male 590 21.25
## 754 Social left female 630 19.92
## 58 Social right male 750 19.08
## 283 Social right female 650 20.17
## 406 Natural right male 570 25.17
## 98 Natural right male 450 22.33
## 564 Social right female 620 19.00
## 54 Social left male 630 19.83
## 341 Social right male 500 19.67
## 277 Social right female 620 18.58
## 578 Social right female 610 20.00
## 464 Natural right female 600 21.17
## 355 Social right male 550 20.33
## 43 Social right female 530 20.33
## 500 Natural right female 620 20.25
## 399 Natural right female NA 19.08
## 263 Natural right male 600 20.08
## 801 Social right female 540 19.08
## 549 Social left female 535 18.08
## 147 Social right female 670 19.25
## 525 Social left female NA 19.83
## 239 Natural right female 550 19.50
## 503 Natural right female 600 19.08
## 924 Natural right male 650 21.58
## 539 Social right female 680 19.17
## 700 Social right female NA 44.00
## 1018 Business left male 450 21.58
## 369 Social right female 480 21.17
## 458 Natural right male 540 19.67
## 204 Natural right female 580 19.25
## 871 Social right female 590 19.25
## 662 Natural right male 510 19.75
## 1076 Business right female 590 18.75
## 345 Social right female 675 21.58
## 780 Social right female 520 19.75
## 240 Natural right female 600 18.92
## 910 Social left female 650 21.08
## 616 Natural right male 600 20.25
## 683 Business left female 590 22.75
## 961 Natural right female 450 34.08
## 75 Natural right female 680 20.75
## 376 Social right female 540 19.17
## 629 Natural right male 600 19.92
## 227 Natural right female 700 19.25
## 469 Natural right male 500 19.25
## 928 Natural right female 680 18.25
## 1031 Business right male 620 20.50
## 656 Natural right male 550 21.33
## 337 Social right female 650 19.42
## 669 Natural right female 600 19.08
## 553 Social right female 620 19.25
## 674 Business right female 620 17.67
## 763 Social right female 550 19.83
## 935 Natural right female 643 18.50
## 386 Natural right female 670 34.67
## 829 Social right female 520 26.17
## 650 Natural right male 750 20.42
## 384 Social right male 780 19.67
## 696 Business right male 530 19.92
## 725 Social right female 580 19.42
## 1000 Business right male 495 18.83
## 711 Social left female 630 19.50
## 109 Natural right female 590 18.92
## 432 Natural right male 480 19.83
## 89 Natural right male 660 18.50
## 658 Natural right female 540 19.58
## 514 Natural left female 560 19.58
## 102 Natural right male 620 18.83
## 898 Social right male 550 18.58
## 893 Social left female 690 19.42
## 895 Social left female 460 20.58
## 8 Social right female 560 19.25
## 200 Natural left female 590 21.50
## 746 Social left female 600 22.25
## 522 Social right female NA 19.00
## 296 Social right male 580 20.83
## 812 Social right female 550 18.33
## 266 Social right female 570 18.50
## 1068 Business right female 540 18.67
## 30 Social right female 730 18.50
## 413 Business right male 610 20.17
## 167 Natural right male 640 19.42
## 41 Social right female NA 20.83
## 677 Business right female 640 20.00
## 457 Natural left male 480 19.08
## 902 Natural left male 560 NA
## 326 Social right male 710 19.42
## 148 Natural right male 720 18.92
## 158 Natural right female 720 17.92
## 1050 Social right male 570 18.67
## 541 Social right female 590 19.00
## 804 Social right male NA 37.42
## 938 Natural right male 720 21.42
## 363 Social right female 680 19.08
## 122 Business left male 480 18.50
## 1027 Business right female 690 19.67
## 506 Natural right female 710 19.58
## 587 Social right male 400 19.50
## 854 Social right female 600 20.50
## 302 Social right male 620 20.00
## 628 Natural right male 580 19.58
## 182 Social right female 500 21.08
## 831 Social right female 620 21.08
## 860 Social right female 600 20.17
## 701 Natural right female 450 NA
## 617 Social right female 760 21.25
## 1129 Natural right female NA 22.25
## 1009 Business right female 500 18.33
## 177 Natural right male 530 21.33
## 526 Social right female 500 20.67
## 731 Social right female 560 19.75
## 163 Natural right male 650 19.33
## 1013 Business right male 500 20.17
## 1066 Business right female 680 19.08
## 439 Natural right male 590 21.08
## 217 Social right female 570 19.08
## 887 Social left female 610 19.17
## 44 Social right female 700 18.83
## 410 Social right female 620 19.00
## 476 Social right female 590 20.25
## 838 Social left male 530 22.00
## 1008 Business right female 610 18.58
## 446 Natural right male 590 23.50
## 134 Natural right female 520 22.08
## 784 Social right male 520 19.08
## 792 Social left female 640 20.08
## 742 Social right female 620 19.17
## 145 Business right male 700 20.17
## 943 Natural left male 650 18.42
## 171 Natural left female 550 18.92
## 806 Social right female NA 20.92
## 168 Natural left female 610 19.58
## 1046 Social left female 480 21.50
## 174 Natural right male 520 19.58
## 809 Social right female NA 25.25
## 912 Natural left male NA 18.33
## 71 Social right male 540 20.25
## 139 Natural right male 600 19.50
## 428 Natural right male NA 19.75
## 1026 Business right female 690 20.83
## 954 Natural right female NA 22.08
## 417 Natural right female 680 19.33
## 1085 Business right female 620 19.67
## 579 Social right female 570 19.58
## 130 Natural right male 490 20.83
## 129 Natural right male 540 19.58
## 717 Social right female 580 19.67
## 641 Natural right male 680 20.25
## 329 Social right female 480 19.25
## 733 Social right female NA 20.50
## 1111 Business right male NA 20.08
## 814 Social right male 510 25.00
## 655 Natural right female 630 18.83
## 383 Social right female 620 18.92
## 603 Natural right female 630 19.33
## 138 Natural right male 550 20.25
## 317 Social right female 700 18.50
random_sample_percent = 100*prop.table(table(random_sample$Handed));random_sample_percent
##
## left right
## 15.625 84.375
pop_percent = 100*prop.table(table(population$Handed));pop_percent
##
## left right
## 13.28609 86.71391
barplot(rbind(pop_percent,random_sample_percent), beside=T, col=c(0,1),legend.text=T,xlab="Handedness",ylab="Percent in Group",args.legend=list(x="topleft"))
random_sample_percent = 100*summary(random_sample$Handed)/length(random_sample$Handed);random_sample_percent; pop_percent = 100*summary(population$Handed)/length(population $Handed);pop_percent; par(mfrow=c(1,2)); pie(pop_percent,labels=paste(c("left=","right="),round(pop_percent,0),"%"),main="Population"); pie(random_sample_percent,labels=paste(c("left=","right="),round(random_sample_percent,0),"%"),main="Random Sample")
## left right
## 15.625 84.375
## left right
## 13.28609 86.71391
random_sample_percent = 100*summary(random_sample$Sex)/length(random_sample$Sex);random_sample_percent; pop_percent = 100*summary(population$Sex)/length(population $Sex);pop_percent; par(mfrow=c(1,2)); pie(pop_percent,labels=paste(c("female=","male="),round(pop_percent,0),"%"),main="Population"); pie(random_sample_percent,labels=paste(c("female=","male="),round(random_sample_percent,0),"%"),main="Random Sample")
## female male
## 61.97917 38.02083
## female male
## 62.09035 37.90965
summary(population$Verbal)
## Min. 1st Qu. Median Mean 3rd Qu. Max. NA's
## 300.0 540.0 590.0 588.8 640.0 800.0 131
summary(random_sample$Verbal)
## Min. 1st Qu. Median Mean 3rd Qu. Max. NA's
## 400 540 590 591 640 780 18
summary(population$Age)
## Min. 1st Qu. Median Mean 3rd Qu. Max. NA's
## 17.67 19.08 19.67 20.37 20.67 74.17 6
summary(random_sample$Age)
## Min. 1st Qu. Median Mean 3rd Qu. Max. NA's
## 17.67 19.08 19.67 20.40 20.65 44.00 2
Creating Similar Treatment Groups
load("computers.RData")
summary(computers)
## age gender comp
## Min. : 18.00 Female:10368 Min. : 0.0
## 1st Qu.: 31.00 Male :10415 1st Qu.: 5.0
## Median : 41.00 Median :11.0
## Mean : 44.27 Mean :11.1
## 3rd Qu.: 55.00 3rd Qu.:17.0
## Max. :107.00 Max. :37.0
random_sample = computers[sample(length(computers$age), 450),]
summary(random_sample)
## age gender comp
## Min. :18.00 Female:228 Min. : 0.00
## 1st Qu.:30.00 Male :222 1st Qu.: 5.00
## Median :42.00 Median :11.00
## Mean :44.27 Mean :11.18
## 3rd Qu.:54.00 3rd Qu.:17.00
## Max. :89.00 Max. :31.00
group = sample(1:3,450,replace=T)
random_sample = cbind(random_sample,group)
boxplot(random_sample$age~random_sample$group, xlab="Group", ylab="Age (years)")
two_way_table = table(random_sample$group,random_sample$gender)
prop.table(two_way_table,1)*100
##
## Female Male
## 1 50.00000 50.00000
## 2 48.34437 51.65563
## 3 53.50318 46.49682
boxplot(random_sample$comp~random_sample$group, xlab="Group", ylab="Computer Use (Hrs/Week)")
