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Figure 1 | BMC Medical Research Methodology

Figure 1

From: Additive scales in degenerative disease - calculation of effect sizes and clinical judgment

Figure 1

Selective vulnerability and task difficulty. f i ( t ; a i , b i , c i ) = a i + b i t e c i ∕ t - 1 , i = 1, 2, tmin ≤ t ≤ t max,.For the orange curve the parameters of the formula in Figure 1 are: a 1 = b 1 = 1, c 1 = -1/6. For the green curve the parameters are: a 2 = b 2 = 1, c 2 = -1/20. The orange curve represents a symptom with a ceiling effect at the beginning of clinical disease (e.g. praxia in Alzheimer's disease), the green curve represents a symptom with a floor effect early during progression of disease (e.g. episodic memory in Alzheimer's disease).

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BMC Medical Research Methodology

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