I am trying to plot two scatter plots on one graph, for some reason, the second scatter is shifted...I don't know why, this is my data:

x

[1] 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30

> y1

[1] 34 30 26 23 21 19 17 16 15 13 12 12 11

> y2

[1] 45 39 34 31 28 25 23 21 19 17 16 15 14

> y2-y1

[1] 11 9 8 8 7 6 6 5 4 4 4 3 3

this is my code:

Code:

```
plot(x,y1, axes=FALSE, col="blue", ylab="Sample size", xlab="Mean difference")
par(new=TRUE)
plot(x,y2 axes=FALSE, col="red", ylab="Sample size", xlab="Mean difference")
```

what am I doing wrong ? According to this graph at some points for a power of 0.8 I need more subjects than for a power of 0.9!