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I have created a linear mixed effects model testing for shannon diversity index, with flower_quantity, temp, precip, wind and cloud cover as continuous variables, and season as a categorical variable. I have created multiple linear mixed effect models to determine the effects of these variables on shannon diversity value.

summary(lmer_model_precip)
Linear mixed model fit by REML ['lmerMod']
Formula: Species_byTF_summary2$SDI ~ Flower_Quantity + (1 | `24h_precip`)
   Data: df2

REML criterion at convergence: -31.2

Scaled residuals: 
    Min      1Q  Median      3Q     Max 
-0.7667 -0.4954 -0.3735  0.2570  1.8948 

Random effects:
 Groups     Name        Variance  Std.Dev.
 24h_precip (Intercept) 7.647e-05 0.008745
 Residual               2.315e-04 0.015215
Number of obs: 8, groups:  24h_precip, 3

Fixed effects:
                Estimate Std. Error t value
(Intercept)      0.06001    0.01213   4.945
Flower_Quantity -0.02689    0.02739  -0.982

Correlation of Fixed Effects:
            (Intr)
Flowr_Qntty -0.778

anova(lmer_model_precip)
Analysis of Variance Table
                npar     Sum Sq    Mean Sq F value
Flower_Quantity    1 0.00022309 0.00022309  0.9637

How do I interpret the output of these summaries and anovas please?

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    $\begingroup$ Welcome to Cross Validated! It's not clear why you are using 24h_precip as a random effect. Random effects typically represent groupings used to handle correlations among observations. Precipitation doesn't seem to be such a grouping. Also, it seems that you are trying to do multiple individual models; it's usually best to do a single model incorporating all predictors. If you only have 8 observations total it will be hard to get useful results in any event. Finally, do check that the modeled residuals are OK, as the Shannon index as an outcome can be poorly behaved in that regard. $\endgroup$
    – EdM
    Commented Dec 13, 2023 at 14:30
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    $\begingroup$ @EdM, I agree with all of this, except that if the OP wants to assess the effects of 5 different predictors (and 24h_precip as a (??) covariate/nuisance variable?), they probably won't be able to fit a multivariate model to a data set with only 8 points ... to the OP: can you tell us a little bit more about how you want to take 24h_precip into account? Is it a *nuisance variable*/covariate you want to control for? How many seasons do you have? $\endgroup$
    – Ben Bolker
    Commented Dec 13, 2023 at 15:53

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