On 24 Jun 2003, Mohammad Ehsanul Karim wrote in part:
< snip, the preliminaries >
< results from a regression analysis: >
> Coefficients:
> Estimate Std. Error t value Pr(>|t|)
> (Intercept) -186075.0 16047.4 -11.60 1.65e-07 ***
> x 2279.4 138.7 16.44 4.33e-09 ***
> ---
> Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1
>
> Residual standard error: 4020 on 11 degrees of freedom
> Multiple R-Squared: 0.9609, Adjusted R-squared: 0.9573
> F-statistic: 270.2 on 1 and 11 DF, p-value: 4.332e-009
> _________________________
>
> Can anyone tell me what are the "Signif. codes"? I think i need a
> bit explanation about specifically each of them. Also what does
> those " * " mean?
These are the same question, in fact. It used to be customary to report
statistical results with one asterisk (*) if the result was significant
at 0.05; with two asterisks (**) if significant at 0.01; or with three
asterisks (***) if significant at 0.001. The line
Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1
is merely defining those asterisk-codes (and including a dot (.) for
significance at 0.10).
It is more usual these days to report the observed P-value (also
reported in your output above, labelled "Pr(>|t|)"). When the P-value
is less than the desired significance level (usually symbolized by the
Greek letter <alpha>), the result is significant at that level; and the
convention of reporting P-values makes it easier for the reader to apply
a significance level different from that used by the original analyst,
should it be desired to do so. The asterisks in your output are really,
therefore, redundant: evidently both 1.65e-07 and 4.33e-09 are less
than 0.001.
> Also, is there any direct command to predict y for x = 110?
Sorry, I don't know R, so don't have an answer for this one. Perhaps
someone else can advise you.
-- DFB.
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Donald F. Burrill [EMAIL PROTECTED]
56 Sebbins Pond Drive, Bedford, NH 03110 (603) 626-0816
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