st: Re: interpreting marginal effects of fractional logit with continuous independent variables

["Sandra Virgo" <Sandra.Virgo@lshtm.ac.uk>]

To David Hoaglin: 
 
Thanks for your advice, which I will take on board. 
 
Best Wishes
 
**** **** 
To Austin Nichols: 
 
It makes sense to me (finally) that a one-unit increase in a proportion is just 0.01, and that this will change my reading of the output. 
 
So when you say that "the y in that expression is not really 'the percentage of conceptions ending in maternity'", do you mean that the y is actually hundredths of a percentage of conceptions ending in maternity?
 
(My output below as reminder)
- ------------------------------------------------------------------------------
    |   Delta-method
    |   dy/dx   Std. Err.   z    P>|z| 
[95% Conf. Interval]
- -
- -------------+----------------------------------------------------------------
  llti_stand |  -.5630636   .0485536   -11.60   0.000  -.658227  
- -.4679002
- -
- ------------------------------------------------------------------------------
 
New interpretation (thanks Austin): 
 
"For every one percentage-point increase in llti_stand
(age-standardised long-term limiting illness prevalence), the percentage
of conceptions ending in maternity decreases by 56 hundredths of a
percentage point (i.e. decreases by just over half a percentage point)?
 
Thanks for your help. 
 
Sandra



Sandra Virgo
PhD Researcher
Department of Population Health
London School of Hygiene & Tropical Medicine
0207 299 4681



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