List clearly and precisely the assessment methods of body composition and put the standard norm for each test based on age ?

1. Dual-energy X-ray absorptiometry (DXA):
- Standard norm for males aged 20-39: 10-20% body fat
- Standard norm for females aged 20-39: 20-30% body fat

2. Bioelectrical impedance analysis (BIA):
- Standard norm for males aged 20-39: 10-20% body fat
- Standard norm for females aged 20-39: 20-30% body fat

3. Skinfold thickness measurements (calipers):
- Standard norm for males aged 20-29: 8-19% body fat
- Standard norm for females aged 20-29: 21-32% body fat

4. Body mass index (BMI):
- Standard norm for males aged 20-39: 18.5-24.9 kg/m²
- Standard norm for females aged 20-39: 18.5-24.9 kg/m²

5. Waist circumference:
- Standard norm for males aged 20-39: <94 cm (37 inches)
- Standard norm for females aged 20-39: <80 cm (31.5 inches)

6. Hydrostatic weighing (underwater weighing):
- Standard norm for males aged 20-39: 10-20% body fat
- Standard norm for females aged 20-39: 20-30% body fat

7. Air displacement plethysmography (Bod Pod):
- Standard norm for males aged 20-39: 10-20% body fat
- Standard norm for females aged 20-39: 20-30% body fat

It's important to note that these standard norms may vary slightly depending on the source and specific age ranges considered. Additionally, individual factors such as genetics, muscle mass, and overall health can influence body composition and may result in variations from these norms.