Table 2 Description of model fitting procedures used in four quantitative statistical models of male An. gambiae age. In all cases, the outcome variable (y) was male age group, defined as 'young' (≤ 4 days), or 'old' (> 4 days). In each model, the relationship between three explanatory variables and the outcome variables of spermatocyst number (x1), proportional size of the sperm reservoir (x2), and the presence or absence of a clear area (x3) was tested. In all models, x3 was treated as a categorical variable, with the treatment of x1 and x2 varying between models as described below (a-d representing distinct categories).
From: A reliable morphological method to assess the age of male Anopheles gambiae
Quantitative Model | Treatment of explanatory variables x1 & x2 | No. of categories | Category definitions | |
|---|---|---|---|---|
Spermatocyst number (x1) | % Size of sperm reservoir (x2) | |||
Continuous | Continuous | n/a | n/a | n/a |
Median | Categorical | 2 | a = 0–2 b = 3–5 | a = < 60% b = ≥ 60% |
Quartile | Categorical | 4 | a = 0 b = 1–3 c = 4 d = 5 | a = ≤ 40% b = 41 – 59% c = 60 – 94% d = ≥ 95% |
Break points | Categorical | 4 | a = 0 b = 1–3 c = 4 d = 5 | a = ≤ 30% b = 31 – 60% c = 61 – 90% d = ≥ 91% |