


| advantages | disadvantages | |
| static | labor | only reflects present conditions |
| cohort | reflect conditions over time | labor |
| Data for hypothetical rats: | |||||||||
| Age Group (months) | (X) | (Nx) | lx | dx | qx | Lx | Tx | ex | |
| 0-3 | 1 | 1249 | |||||||
| 4-7 | 2 | 820 | |||||||
| 8-11 | 3 | 730 | |||||||
| 12-15 | 4 | 505 | |||||||
| 16-19 | 5 | 405 | |||||||
| 20-23 | 6 | 225 | |||||||
| 24-27 | 7 | 75 | |||||||
| 28-31 | 8 | 35 | |||||||
| 32-35 | 9 | 0 |
| Age Group | (x) | lx | bx | lx x bx = Vx | lxbxX | |
| 0-14 | 0 | 0.9836 | 0.0030 | 0.0030 | 0.0 | |
| 15-29 | 1 | 0.9751 | 0.6918 | 0.6746 | 0.6746 | |
| 30-44 | 2 | 0.9583 | 0.2049 | 0.1964 | 0.3928 | |
| 45+ | 3 | 0.9453 | 0.0005 | 0.0005 | 0.0015= | Sum 1.0689 |
| Ro = sum of lxbx = 0.8745 |
| Age Group | (x) | lx | bx | lxbx=Vx | lxbxX |
| 0-4 | 0 | 1.00 | 0.03 | 0.03 | 0.00 |
| 5-9 | 1 | 0.69 | 0.89 | 0.61 | 0.61 |
| 10-14 | 2 | 0.49 | 0.55 | 0.27 | 0.54 |
| 15-19 | 3 | 0.15 | 0.02 | 0.00 | 0.00 |
| 20-24 | 4 | 0.00 | 0.00 | 0.00 | 0.00 |
| # of prey | immediately lethal | eventually lethal | % consumed | |
| True Predators | Many | YES | - | large |
| Grazers | Many | NO | small removal-No | small-large |
| large removel-Yes | ||||
| Parasites | One to few | NO | small load - No | small |
| large load - Yes | ||||
| Parasitoids | One to few | NO | YES | eventually large |
| Defense: | morphology | Examples: porcupines, blowfish, and frilled lizard |
| biochemical | Examples: plant toxins, frog, toad toxins, skunks, poisonous | |
| Avoidence: | temporal | Examples: Deer |
| spatial | Examples: amphibians | |
| Escape: | Confusion | Examples: lizard tail |
| Speed | Examples: Gazelles |
| Sample | P1(mm) | P1^2 | P2(mm) | P2^2 | P1^2 / P2^2 = Xi | Xi^2 |
| 1 | 3 | 9 | 10 | 100 | 0.0900 | 0.0081 |
| 2 | 5 | 25 | 8 | 64 | 0.3906 | 0.1526 |
| 3 | 10 | 100 | 12 | 144 | 0.6944 | 0.4822 |
| 4 | 9 | 81 | 10 | 100 | 0.8100 | 0.6561 |
| 5 | 18 | 324 | 25 | 625 | 0.5184 | 0.2687 |
| 6 | 4 | 16 | 6 | 36 | 0.4444 | 0.1975 |
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