Without a control you have no idea what is actually causing an effect or whether the effect is merely the result of the experimental procedure itself. If your test is different from your control(s) then you can claim there is a significant difference.
I've touched on the subject before and think it's useful to try and point out other examples. It should hopefully appeal to the
The first instalment turns out to be an actual victory for control freaks! So, this morning, I'm sure a lot of you may have encountered on your social media an article about some pretty disgusting micro-fibres turning up in a MacDonald's chicken nugget by upworthy. Now I'm not defending MacDonald's here at all but the video only showed a chicken nugget from a MacDonald's store. The problem here is that without a control, the disturbing results are meaningless. Why is this? Well, do you know what a chicken nugget prepared by your own loving hands looks like under high magnification? If not, then how do you know that chicken nugget wouldn't look exactly the same when put through the same experiment? Maybe the fibres are from someone preparing the sample for magnification and have nothing to do with MacDonald's? Why not look at a few other food types eg a chicken breast you've cooked and see what turns up there? If any of those things contain the same array of fibres then it is something intrinsic in all chicken based food OR the preparation of the sample for microscopy introduces the fibres into the food.
The experiment should compare as a minimum these three things:
"A MacDonald's chicken nugget prepared outside of MacDonald's store"
"A MacDonald's chicken nugget prepared in a MacDonald's"
"A non MacDonald's chicken nugget made from original ingredients outside a MacDonald's store"
I have to commend Upworthy for listening to readers' complaints (before MacDonald's lawyers told them), which I'm sure are along the lines of what I have just outlined. If they produce a similar video with an appropriate control and it still appears that the MacDonald's sample has far more fibres in it then I'll be far more convinced and disgusted by the video.