3 groups, 3 measurments for each, three replication
0
0
Entering edit mode
8.8 years ago

I'm very new in the field I'm working now and have a simple question:

If I'm given such following data:

conds <- rep(c("old","young","kid"),each=9)
measures <- rep(rep(c("weight","height","heartbeats"),each=3),3)
values <- c(sample(50:100,9),sample(150:190,9),sample(60:120,9),
            sample(50:110,9),sample(150:200,9),sample(60:120,9),
            sample(5:50,9),sample(50:150,9),sample(60:100,9))
d <- data.frame(measures,conds,values)

How can I do test the differences between old vs young, old vs kid and kid vs young considering all other measures together?

These are two ways I used to find the differences between each pairs of old-young-kid based on the observed measures but I think non of these are correct:

aov.out = aov(values ~ conds , data=d)
summary(aov.out)
               Df Sum Sq Mean Sq F value Pr(>F)  
    conds        2  14515    7257   3.643 0.0415 *
    Residuals   24  47811    1992                 
    ---
    Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
     TukeyHSD(aov.out)
      Tukey multiple comparisons of means
        95% family-wise confidence level

    Fit: aov(formula = values ~ conds, data = d)

    $conds
                   diff        lwr       upr     p adj
    old-kid   47.000000  -5.543622  99.54362 0.0856646
    young-kid 51.111111  -1.432511 103.65473 0.0576516
    young-old  4.111111 -48.432511  56.65473 0.9791911

I decided to reorder my data and find the differences in the following way:

conds <- rep(c("old","young","kid"),each=3)
w <- values[c(1:3,10:12,19:21)]
h <- values[c(4:6,13:15,22:24)]
hb <- values[c(7:9,16:18,25:27)]
d <- data.frame(conds,w,h,hb)
av.out <- aov(w*h*hb~conds,d)
     summary(av.out)
                Df    Sum Sq   Mean Sq F value  Pr(>F)   
    conds        2 3.075e+12 1.537e+12    13.4 0.00612 **
    Residuals    6 6.885e+11 1.147e+11                   
    ---
    Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
     TukeyHSD(av.out)
      Tukey multiple comparisons of means
        95% family-wise confidence level

    Fit: aov(formula = w * h * hb ~ conds, data = d)

    $conds
                 diff     lwr     upr     p adj
    old-kid   1172527  323913 2021141 0.0128705
    young-kid 1297829  449215 2146443 0.0079956
    young-old  125302 -723312  973916 0.8949227

Would you let me know which is correct? if none of them are correct then how could I find the differences?

Thanks,

Maah

statistics anova • 1.9k views
ADD COMMENT

Login before adding your answer.

Traffic: 1853 users visited in the last hour
Help About
FAQ
Access RSS
API
Stats

Use of this site constitutes acceptance of our User Agreement and Privacy Policy.

Powered by the version 2.3.6