Question

You are an entrepreneurial microbiologist and started a bio-remediation company manufacturing bacterial strains that breakdown hydrocarbons in marine environments (think oil spills). You are evaluating two promising strains, but you suspect they have optimal efficiency at different temperatures – which has implications for where you will deploy them. You set up an experiment to evaluate the two strains (A and B) at two temperatures (10º C = Gulf of Maine, and 30º C = Gulf of Oman). You set up replicate flasks and the data are grams of hydrocarbons broken down by 1 ml of standard bacterial cell culture at the two temperatures: Aat10 = strain A at 10º, Aat30 = strain A at 30º C; Bat10 = strain Bat 10º, and Bat30 = strain B at 30º C.

What type of statistical test do you use?

Answer 1

These type of problems involve utilising all your knowledge of different types of statistical tests and using them appropriately

I would use two-sample ANOVA test here since we are given two different bacterial strains i.e., A and B

which will be our varieties(or row factors whichever terminologhy you prefer) and the temperatures at which grams of hydrocarbons are broken down by 1 ml of standard bacterial cell culture i.e., Aat10, Aat30 and Bat10, Bat30 will be our treatments(or column factors whichever terminolgy you prefer). So the table would look like this. I will be using the terminologies treatments and varieties since I am comfortable with that but you can also use the row factor and column factor terminology.

Varieties\Treatments	Aat10	Aat30	Bat10	Bat30
A
B

So you just enter the data and depending on the data, the number of fields in the Treatments columns(Aat10, Aat30,Bat10 and Bat30) may change. This is just a rough outline of how the initial  table would like in our case.

To explain why I kept the temperatures at which grams of hydrocarbons are broken down by 1 ml of standard bacterial cell culture as treatments(or column factors) was because the bacterial strains are our two varieties(row factors) and the treatment we are subjecting them to is temperature i.e., we are taking these strains in replicate flasks and subjecting to different temperatures which I already mentioned above and is also given in the question.

So if you are interested in knowing what the null hypothesis(the alternate hypothesis is the converse of the null hypothesis), it is that:

Null hypothesis

There is no significant difference in the optimal efficiency at the given temperatures i.e., the bacterial strains efficiency is the same for both the temperatures.

There is no significant differance in the optimal efficiency for the bacterial strains i.e., there is no difference of efficiency between the two strains at the same temperature.

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