This page contains answers to frequently asked questions (FAQs) about alpha. If this page does not help you solve your problem, please let us know . Select the question from the list below to see the answer.

	What are the ways of expressing risk?
	What are Truncation Limits?
	What is meant by capping a risk estimate?
	How do I estimate centile values?
	How are detection and false-positive rates estimated?
	How do I check my false-positive rate ?
	How can I check if my false-positive rate is what it should be?
	How can I check that my normal median values are accurate?
	I plan to change from RIA kits to a non-radioactive method. Do I need to change anything in alpha?
	How can I see if predicted risk estimates in my screening programme are accurate?
	What are the confidence intervals on my Down's syndrome detection rate?
	I want to add inhibin-A to my screening program. Can I do this with alpha?
	A diabetic woman has an AFP level of 2.1 MoM - why does alpha say her AFP is raised, when my cut-off is 2.5 MoM?
	How does alpha interpret nuchal translucency (NT) and first trimester serum markers in a twin pregnancy?
	I want to analyse my screening data using Microsoft Excel. Can I transfer the data from alpha into a spreadsheet?
	Can alpha be interfaced with other computer systems or laboratory equipment?
	Why is the risk of trisomy 18 not shown on reports when it is below the cut-off?
	Can a warning be given if the screening result appears to be heavily influenced by a single marker measurement?
	Why is the screening report positive when a previous pregnancy is affected with Down's syndrome or neural tube defects?
	Why is screening for neural tube defects not carried out at 14 weeks?
	What is the "scan update rule"?
	What is the best gestational age for first trimester tests?
	Why does Alpha not show separate risks for each fetus in a twin pregnancy?
	Can I specify which set of normal medians to use?
	What maternal age related risk equation does Alpha use?
	Why does Alpha not use a second maternal weight with a second sample in the Integrated test?
	What does it mean when a MoM value falls outside the 95% confidence interval around 1.0 MoM?
	How does Alpha make adjustments for in-vitro fertilization pregnancies?
	Why is the screening result for neural tube defects based on the AFP MoM value and not on the risk estimate?
	Why does Alpha not draw attention to markers which are individually high or low?
	When should women who are diabetic be identified as such in Alpha?

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