Table 1.
Descriptive Statistics of Study Variables by Year
| Mean | Standard deviation | Range | |
|---|---|---|---|
| 1998 (n = 8,524) | |||
| Age | 69.18 | 7.07 | 60–97 |
| Work status | .53 | .80 | 0–2 |
| Immediate memory | 5.69 | 1.74 | 0–10 |
| Physical disability (ADL) | .40 | .99 | 0–6 |
| Depressive symptoms (CES-D) | 1.47 | 1.84 | 0–8 |
| 2000 (n = 8,270) | |||
| Work status | .41 | .73 | 0–2 |
| Immediate memory | 5.40 | 1.73 | 0–10 |
| Physical disability (ADL) | .42 | 1.00 | 0–6 |
| Depressive symptoms (CES-D) | 1.43 | 1.82 | 0–8 |
| 2002 (n = 8,178) | |||
| Work status | .34 | .67 | 0–2 |
| Immediate memory | 5.31 | 1.67 | 0–10 |
| Physical disability (ADL) | .42 | 1.02 | 0–6 |
| Depressive symptoms (CES-D) | 1.44 | 1.89 | 0–8 |
| 2004 (n = 8,164) | |||
| Work status | .28 | .60 | 0–2 |
| Immediate memory | 5.04 | 1.65 | 0–10 |
| Physical disability (ADL) | .52 | 1.20 | 0–6 |
| Depressive symptoms (CES-D) | 1.43 | 1.87 | 0–8 |
| 2006 (n = 8,319) | |||
| Work status | .22 | .54 | 0–2 |
| Immediate memory | 4.87 | 1.71 | 0–10 |
| Physical disability (ADL) | .75 | 1.47 | 0–6 |
| Depressive symptoms (CES-D) | 1.49 | 1.91 | 0–8 |
| 2008 (n = 8,206) | |||
| Work status | .20 | .51 | 0–2 |
| Immediate memory | 4.84 | 1.68 | 0–10 |
| Physical disability (ADL) | .84 | 1.57 | 0–6 |
| Depressive symptoms (CES-D) | 1.45 | 1.90 | 0–8 |
Note. ADL = Activities of Daily Living scale; CES-D = Center for Epidemiologic Studies-Depression scale.