Questions
- Simulate data for 30 draws from a normal distribution where the means and standard deviations vary among three distributions.
# place the code to simulate the data here
set.seed(16)
rnorm(30,mean = c(0,15,20),sd=c(2,12,22))
## [1] 0.9528268 13.4954400 44.1167564 -2.8884581 28.7739515
## [6] 9.6949351 -2.0119012 15.7627521 42.5493972 1.1462840
## [11] 37.1661852 22.4625341 -1.4920746 34.8985639 35.8778525
## [16] -3.3261610 21.9109144 30.4007226 -1.0854633 28.5322449
## [21] -16.2515476 -0.6283479 12.8078212 52.3505268 -1.7317976
## [26] 33.3296038 43.1919173 2.0601420 25.0819303 24.7732235
- Simulate 2 continuous variables (normal distribution) (n=20) and plot the relationship between them
# place the code to simulate the data here
X=rnorm(20,mean=10,sd=10)
Y=rnorm(20,mean=10,sd=10)
plot(X~Y)
- Simulate 3 variables (x1, x2 and y). x1 and x2 should be drawn from a uniform distribution and y should be drawn from a normal distribution. Fit a multiple linear regression.
# place the code to simulate the data here
set.seed(15)
x1=runif(30,min=0,max=30)
x2=runif(30,min=30,max=100)
y=rnorm(30,mean = 10,sd=2)
lm(y~x1+x2)
##
## Call:
## lm(formula = y ~ x1 + x2)
##
## Coefficients:
## (Intercept) x1 x2
## 8.40045 0.02279 0.02868
- Simulate 3 letters repeating each letter twice, 2 times.
# place the code to simulate the data here
rep(letters[5:7],each=2,times=2)
## [1] "e" "e" "f" "f" "g" "g" "e" "e" "f" "f" "g" "g"
- Create a dataframe with 3 groups, 2 factors and two quantitative response variables. Use the replicate function (n = 25).
data.frame(group = rep(letters[4:6]),
factor = rep(LETTERS[6:7]),
x = rnorm(30, mean =0, sd=1),
y = rnorm(30, mean = 10, sd =15))
## group factor x y
## 1 d F 0.298601577 -1.640431
## 2 e G -0.427671565 -9.772237
## 3 f F -0.589199432 41.560901
## 4 d G -1.296619746 15.682816
## 5 e F -1.487791903 6.638860
## 6 f G -1.160348729 33.278334
## 7 d F -0.332793231 7.448808
## 8 e G 0.542287542 29.269665
## 9 f F -0.740264300 -5.030834
## 10 d G 1.241494105 -26.562308
## 11 e F -1.525213383 9.399614
## 12 f G -1.876918033 9.555150
## 13 d F -1.326949625 -8.121199
## 14 e G -0.496877106 31.980078
## 15 f F 0.040101820 26.186630
## 16 d G -0.544629514 4.978399
## 17 e F 0.360012921 13.079430
## 18 f G 1.003106596 23.820814
## 19 d F -0.982049982 -28.811118
## 20 e G 2.040274306 16.241093
## 21 f F 0.003183053 -3.100353
## 22 d G 2.335035528 19.353651
## 23 e F 0.154263359 12.082491
## 24 f G -0.465579380 16.090965
## 25 d F -0.469543894 15.005901
## 26 e G -0.496542207 19.177405
## 27 f F -0.322340429 -12.625296
## 28 d G 0.614664971 3.104069
## 29 e F 0.127627263 25.821625
## 30 f G -0.151659147 7.040857