Hello!
I have measurements (length and volume) of fish collected in two years. I
want to know if the the relationship between length and volume is the same
for both years. The number of fish measured is different for each year. I
don't know whether lm or aov is more appropriate to use.
Here are the two output options:
Call:
lm(formula = Volume ~ Length * Year)
Residuals:
Min 1Q Median 3Q Max
-1.35062 -0.42695 -0.02234 0.29789 1.78540
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -8.699125 0.543372 -16.010 <2e-16 ***
Length 0.151462 0.006708 22.578 <2e-16 ***
Year1 1.627903 1.168158 1.394 0.1660
Length:Year1 -0.024259 0.014510 -1.672 0.0972 .
---
Signif. codes: 0 *** 0.001 ** 0.01 * 0.05 . 0.1 1
Residual standard error: 0.6016 on 119 degrees of freedom
Multiple R-squared: 0.8384, Adjusted R-squared: 0.8343
F-statistic: 205.8 on 3 and 119 DF, p-value: < 2.2e-16
----
AND for aov:
----
Df Sum Sq Mean Sq F value Pr(>F)
Length 1 219.457 219.457 606.4349 < 2.2e-16 ***
Year 1 2.970 2.970 8.2073 0.004934 **
Length:Year 1 1.012 1.012 2.7952 0.097173 .
Residuals 119 43.064 0.362
---
Signif. codes: 0 *** 0.001 ** 0.01 * 0.05 . 0.1 1
Thanks very much for any help.
Kirsten
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