MMUPHin lm_meta: Questions regarding warning messages and forest plot generate


I am new born in field of bioinformatics and i am glad to using MMUPHin R packages for meta-analysis of gut microbiome 16S sequencing data.

I use this tool to detect different abundance microbes based in different disease states, compare with healthy controls.

I have 3 questions regardless MMPHin tool.

  1. i run the lm_meta after batch/study correct,

data_meta$Host_case_disease ← relevel(x = as.factor(data_meta$Host_case_disease), ref = “disease_type”)

I have not another variables to check only the different type of disease

fit_lm_meta ← lm_meta(feature_abd = data_abd_adj,
batch = “Bioproject”,
exposure = “Virus”,
covariates = c(“Host_case_disease”),
data = data_meta,
control = list(verbose = FALSE))

meta_fits ← fit_lm_meta$meta_fits

my question is, if someone knows what is mean this warnings ?

Fisher scoring algorithm may have gotten stuck at a local maximum.
Setting tau^2 = 0. Check the profile likelihood plot with profile().

I cannot find something that explain how to explain me for Fisher algorithm or i am not so good to find something. The only think i know is the tau^=0 mean no heterogeneity so i can combine the datasets.

  1. I use the same code with out covariates and the warning just disappear
    so my question is, can i don’t use covariates ?

  2. can i produce forest plot based random effect model based in MMPHin tool?
    so i can compare the different state of disease like paired-test

I am sorry for so match question, If anyone can help, it would be greatly appreciated!!!

Thanks for your support