## Two-Tailed *p*-Value and Confidence
Limits

The two-tailed p-value indicates the statistical
significance associated with testing whether the slope of the
dose-response curve is different from zero. All values are given to
one significant figure. When there is no dose-related effect or the
slope is negative, then “P=1.” appears. The lowest
*p*-value reported is *p*<0.0005.

Lower and upper 99% confidence limits are shown
for each TD_{50}. When the abbreviation
“n.s.s.” appears for either the lower or upper
confidence limit, it denotes not statistically significant.
Whenever the statistical significance of TD_{50} is
*p*>0.01, then the upper 99% confidence limit will not be
calculated. When the lower confidence limit is “n.s.s.”
this usually indicates that there were no tumors or only one tumor
of the specified type in the experiment, and the lower confidence
limit was not estimable. Occasionally the n.s.s. occurs for the
lower confidence limit because 100% of dosed animals had the
tumor(s) of interest and hence no lower confidence limit could be
estimated with summary data.

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