Using two different strains of KO mice I have completed running them through 'marble burying' as an indication for anxiety. The mice also went through an Elevated Zero Maze.
I'm trying to figure out the best way to describe my results.
'A' KO MICE:
The 'A' KO mice were much more exploratory and spent increased amount of time in the exposed areas of the Elevated Zero Maze (EZM), therefore indicating decreased anxiety or fear.
These same 'A' KO mice buried more marbles than the wild type mice. The WT buried around 4-8 marbles whereas the KO mice buried 14-18.
Literature that I've read indicates that this might be a sign of increased anxiety or OCD behaviour, but the EZM results contradict this.
'B' KO MICE"
These mice had a completely different genetic mutation compared to the 'A' mice. These 'B' KO mice buried little to no marbles. They also spent more time in the enclosed/"safe" areas of the EZM.
When these mice were administered 0.1mg/kg dose of Diazepam their marbles burying increased to about 10 marbles. I would therefore want to deduce that the diazepam "normalised" their behaviour bringing their number of marbled buried close to the WT value.
What I want to discuss is: does this mean that the 'B' KO mice have a tendency towards an anxious phenotype and that little to no marble burying indicates this? And therefore does burying MORE marbles show that the 'A' KO mice are less anxious?
Does little to NO marble burying indicate an anxiety prone phenotype?
Does burying almost ALL marbles indicate a less-anxiety prone phenotype?
You can check out our papers how we reported in genetically selected mice (not KO) anxiety and exploration and so on if they give you any idea.
Age and sex differences in anxiety and differences in freezing responses as well as in Thigmotaxis and pattern of urination and defecation are all indices of anxiety. So you need to compute sex differences too. I assume that all your mice are of the same age. We consider 100 days as a good age for experimentation as a general rule.
In Wikipedia it says that "younger mice will bury marbles faster than older mice so the age of the mice being tested must be the same". Rodents are placed for thirty minutes in a standard cage filled with 5 cm depth of wood chip bedding with 10 marbles evenly spaced. After thirty minutes the amount of marbles buried is measured. In this procedure a marble is considered buried if 2/3 of the marble is covered with bedding. Within the study there should be two groups of animals, one group which has been injected with saline and another group which has been injected with the agent being tested.
There are multiple variations of this test. Some experiments use more marbles while other variants place the marbles differently.
It is important to keep the laboratory quiet while performing this experiment to avoid unintended results.
We also did a test how mice are retrieving their newborns and if males are as good parents as female mice although they cannot feed the pups. We called it pullus index and check how a new born compared with a familiar nest (nidus index)
Our paper confirms the sex difference in the mouse behaviors:
Swiss albino mice (Mus Musculus L.) were studied in an open field (OF). The question whether laboratory rodents were more attracted to a nest equipped with familiar odoriferous cues from the home-cage bedding or to signals of an unfamiliar newborn pup inserted in the OF was addressed. The results of the three quantitatively recorded OF behaviors, ambulation, retrieval and radial latency, indicated that in females both ambulation and retrieval were enhanced by the presence of a pup in a nestless field; in males locomotion was suppressed by a nest in a pupless OF. In the case of both sexes radial latency was determined by the OF position of a nest. A comparison between the two qualitative assessments, the nidus and pullus indices, yielded that the sex of the adult and the OF positions of both targets equally impacted attraction towards both nest and pup.
First thing to be careful of is that marbles come in multiples of one. So you will need negative binomial regression or Poisson regression, with robust standard errors and observations clustered within mice.
The second really interesting thing is that you have a zero observed event rate in one arm of your trial. A one-sided 97.5% CI for your rate will depend on your sample size. If you have the usual 6 animals, the upper limit is about 0.6, and for 12 animals it's about 0.3. So it does make sense to test unless you have large numbers.
Now we come to the really important bit. What is your hypothesis?
Without knowing that, no-one can really recommend a statistical procedure. (Unless they are an SPSS user with one of those decision charts that takes all the thinking out of science.)