D-I of Research (Science to English Dictionary: Part 2)

To explain independent and dependent variables, let’s look at a very simple setup: Imagine you have a toy car speeding down a ramp and you want to know how far it has travelled at different points in time. 

Towards this, you might make a two column table:

In this situation, time and distance are both variables– they are values that change over the course of the experiment. Now the question goes, which variable depends on the other? Will changing the distance of the car change the time on the clock? No, but as the time on the clock changes, the distance will change. In this case, distance is the dependent variable and time is the independent variable. Distance changes as time changes. In almost all cases, time will an independent variable

On an x/y graph, the independent variable is plotted on the x (horizontal) axis, and the dependent variable is plotted on the y (vertical) axis.

We explained blinded studies in our article about Oxford’s COVID19 vaccine candidate. In case you didn’t catch it then, here it is again:

For this explanation, let’s imagine a checkout counter at a store. You are buying something. I am behind the counter as a cashier. In this case, let’s designate you as the participant and me as the experimenter. Let’s say that this is a very bad store where there are only two types of shirts being sold: t-shirts and tank tops.

In a single-blinded study, you as the participant would not know whether you are buying a t-shirt or a tank top. All you would know is that you’re holding a mysterious brown packet that is a type of shirt, and that you’ve now brought it to the counter to check out. As the experimenter, I would know whether you have a t-shirt or a tank top. While you are ‘blinded’ to which category you’re in, I am not. This is a single-blind study.

In a double-blind study, neither you nor I know what’s in the packet. All I know is that you have either a shirt or a tank top and have come to the counter to check out. All you know is you’ve bought some sort of shirt. In this case, we are both blinded to the category you’ve fallen into- so this is a double-blind study.
In the case of a double-blind study, the actual categories are stored in a database somewhere or blacked out of the data files before scientists analyze them. Single or double-blinded studies help make sure that the results aren’t biased- either by patient behaviour or by the experimental analysis, or both.

Evidence is gathered by pooling together relevant observable facts and data collection to show that a suggestion is valid or is indeed true. Evidence can be used to support a fact. In science, empirical evidence is gathered through experiments that are recorded and analysed. This evidence is then used to test and then support or counter a theory or hypothesis. 

Typically, a fact is something that is known to be true, like saying the “the sky is blue.” Facts can also be proven true through data collection and observation. In a scientific sense, facts are usually objective and observed multiple times to be stated. For example, it can be said that it is a scientific fact that HIV infects CD4 cells.

Generally in the scientific community, a hypothesis can be defined as a proposed explanation for a phenomenon or idea. This hypothesis can then be studied and investigated further. Hypotheses can be drawn from a limited amount of data, but making a hypothesis then triggers further investigation to gather more evidence. This evidence will lead to the hypothesis being supported or disproved.

When an experiment is done ‘in-silico,’ that means that it was done on a computer or through using a computer simulation. For an example, check out Rosetta, one of the coolest methods of in-silico protein design.

An ‘in-vitro’ experiment is defined as an experiment that was carried out in a test tube, a culture dish or in some other model that is outside of a living organism. Cell-based experiments are in-vitro experiments.

‘In-vivo’ experiments are carried out on living creatures, such as animal or human models.

A lot of vaccines contain inactivated virus particles. When a virus is ‘inactivated,’ it is treated in a way that makes it incapable of infecting cells. However, your immune system is still capable of recognizing it. This gives us the best of both worlds- an immune response without all the nastiness of getting sick!

See dependent variable.