25–29
Table 1.4 Descriptive statistics for the Quasar Data. Luminosity in log‐scale (
| Variable | Min | Q1 | Q2 | Mean | Q3 | Max |
|---|---|---|---|---|---|---|
| X |
 |
 |
0.39 | 0.24 | 0.71 | 2.08 |
| U |
 |
 |
 |
 |
0.26 | 0.75 |
| V | 0.15 | 1.78 | 2.10 | 1.95 | 2.36 | 2.58 |
The Quasar Data are used in Chapter 3. This classical example is also included in the DTDA package (dataset Quasars).
1.4.5 Parkinson's Disease Data
Clark et al. (2011) investigated the association of candidate single nucleotide polymorphisms (SNPs) and age of onset of Parkinson's disease (PD). For this, genomic DNA samples from human blood samples were obtained from the National Institute of Neurological Disorders and Stroke (NINDS) Human Genetics DNA and Cell Line Repository at the Coriell Institute for Medical Research (Camden, New Jersey). More specifically, one aim of the study was to detect association between the rs8192678 PGC‐1a and A10398G SNPs and the risk or age of onset of PD.
Table 1.5 Parkinson's Disease Data: age of onset for genetic groups. Early onset: 35–55 years; late onset: 63–87 years. Sample size
| Group | SNP | Alleles |
 |
Mean (SD) |
|---|---|---|---|---|
| Early onset | A10398G | A | 76 |
46.93  |
| G | 21 |
47.14  |
||
| PGC‐1a | A | 8 |
50.00  |
|
| AG | 50 |
47.18  |
||
| G | 39 |
46.10  |
||
| Late onset | A10398G | A | 73 |
  |
| G | 27 |
75.33  |
||
| PGC‐1a | A | 10 |
74.00  |
|
| AG | 37 |
76.49  |
||
| G | 53 |
74.49  |
In order to remove the selection bias related to survival, the study was limited to patients diagnosed from PD who had their DNA sample taken within 8 years after onset. Consequently, the age of onset
