Then i started to fit a model to the data. I was surprised that when i fitted a simple linear model the regression coefficients were significant:

Code:

```
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 5.1904 0.1347 38.53 <2e-16 ***
nucsomeI$med -2.1237 0.1090 -19.48 <2e-16 ***
```

Eye-balling the plot i thought an exponential model might be a better choice, so i tried:

Code:

```
Formula: nucsomeI.insert_count ~ exp(a + b * nucsomeI.med)
Parameters:
Estimate Std. Error t value Pr(>|t|)
a 2.19786 0.02950 74.50 <2e-16 ***
b -1.89507 0.09435 -20.08 <2e-16 ***
```

That said, i'm probably doing something stupid, so any help much appreciated.