Product Catalog
Generic Norplant (Lenor - 72, Norplant® equivalent)
Lenor - 72 is a form of progesterone, which is a female hormone involved in conception. Lenor - 72 is used as an emergency contraceptive (EC) to prevent pregnancy after contraceptive failure or unprotected intercourse. Lenor - 72 prevents ovulation disrupts fertilization, and inhibits implantation.
This product will arrive to you in 14-24 business days (free shipping worldwide)
0.075mg
| Quantity | Price | Price per pill | Returning customer price | Bonus | |
|---|---|---|---|---|---|
| 2 | € 21.30 | € 10.65 | € 19.17 | ---- | Add to cart |
| 4 | € 24.85 | € 6.21 | € 22.01 | ---- | Add to cart |
| 6 | € 27.69 | € 4.62 | € 24.85 | ---- | Add to cart |
Drug Medical Information
AGE AND BEHAVIOR: ADVANTAGES OF LONGITUDINAL STUDIES
It is clear that if it is not possible to carry out simultaneously both cross-sectional and longitudinal studies, then, all things being equal, the longitudinal study is the method of choice. All things are not equal, however; the longitudinal method is much more difficult to carry out. Fortunately, not all questions require research with this more difficult method. The cross-sectional method is appropriate for answering many questions. Let us examine why the longitudinal method is the more advantageous, and then, what some of its special problems are.
Advantages
The longitudinal method is the only possible method for charting changes over time for the individual person. Not only does this method permit measurement of average changes for the individual, it also permits analysis of intra-individual (within the individual) variations. Such analysis often has value, not only for theoretical purposes but for practical applications as well. For example, if during the period of testing at time 1, a subject's performance scores vary by 10 units, but during the same testing period at time 2 they vary by 100 units, the experimenter might develop hypotheses important to the subject. There may be a loss of interest or motivation to maintain sustained attention, there may be a transient personal problem, but the experimenter might look also for signs of arteriosclerosis, or other states making for inconsistency. Cardiovascular problems could keep the amount of blood reaching the brain very variable; since the brain needs the nourishment carried by the blood, performance may be expected to be variable. The experimenter may suspect nervous system pathology, especially if cardiovascular disease is not apparent. It is only in longitudinal research that the individual may be so examined.
Longitudinal research has other advantages too. It is becoming almost routine in long-term longitudinal projects to examine retrospectively differences between survivors and those who have died. A later section, "Sampling," discusses this from a different aspect, but here the relevant questions are: Which of the measurements made earlier in the longitudinal study, and in what combinations, differentiate the later survivors from those who have died? Which functions, and what combination of them, appear to be predictive of impending disease? A most meaningful strategy, one very costly to carry out, is to make such retrospective analyses and then, following this, make prospective analyses in a subsequent longitudinal study. The first longitudinal, retrospective study should be the basis for the hypotheses tested in the second longitudinal, prospective study.
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