The Student Room Group
Reply 1
yellowdots
Hi, im finding 1 and 2 tailed tests really difficult to understand as i'm awful at statistics. For example, would something like 'boys are more likely to be dyslexic than girls' be a 1-tailed test?
Also, does anyone know an easy way to learn what they mean, becuase i've looked everywhere and cant find an understandable explanation anywhere?
Thanks :smile:


Hi i had difficulty understanding that at first as well I also got confused about null and research hypothesis...i still get confused sometimes.:s-smilie:

Here's a definition I hope it helps: :smile:

When we make a prediction about the outcome of an experimental situation it may be one of two types. If we are very confident about the nature of the outcome we might predict that our manipulation of the independent variable will cause a specific change in the dependent variable, e.g. we may predict a positive change (or we might be predicting a negative change). This would be called a one tailed hypothesis because we are only predicting one possible outcome.

However, in another situation, if we were less confident about the specific outcome, i.e. the change in the dependent variable might be positive or negative (both of which might be acceptable), then we have a two tailed hypothesis. Two tailed because two outcomes are possible, or more correctly because we are not predicting the direction of any specific outcome.


http://www.chssc.salford.ac.uk/healthSci/resmeth2000/resmeth/tailshyp.htm

For your example about boys being more dyslexic then girls that would be a one tailed hypothesis....i think.
Reply 2
oh ok that makes more sense to me now :smile: thanks for your help!
Reply 3
for a 1 tailed test you already know the outcome so basically your hypothesis is:
'X causes/affects/has something to do with Y'. it's definitive.

for a 2 tailed test,you're not sure what will happen so your hypothesis is:
'we are testing to find out whether X affects/causes/has something to do with Y'

in both cases your null hypothesis is that ' there is no relationship between X and Y'.

:smile:
Reply 4
Yep one-tailed means that you are predicting a certain thing will happen (e.g. X will be more than Y, X will increase Y etc) and two-tailed means you're just predicting some relationship (e.g. X will affect Y) but you're not predicting exactly how it will affect it.
1 tailed - You predict the way it goes. E.g: "The time taken to learn the emotional words will be significantly more than time taken to learn the neutral words

2 tailed - You predict there's a difference. Just don't state the direction. E.g: There will be a significant correlation between the two stress questionnaires.

Just examples.

And then there's the null hypothesis. Where you predict there will be no significant correlation/difference.

It took me 2 years of college to understand lol :smile:
Reply 6
My teacher gave us a way to remember it...

With a one tailed hypothesis if you draw a fish with one tail it is going in one direction... i.e. the hypothesis actually states the direction of the prediction

With the two tailed hypothesis the fishy has two tails so it can go in either direction!

Hope that makes some sense?! :biggrin:
Reply 7
xSweetheartx
My teacher gave us a way to remember it...

With a one tailed hypothesis if you draw a fish with one tail it is going in one direction... i.e. the hypothesis actually states the direction of the prediction

With the two tailed hypothesis the fishy has two tails so it can go in either direction!

Hope that makes some sense?! :biggrin:


that actually does make sense lol, thanks for that!
Reply 8
You're welcome :smile:
Reply 9
Thanks for the rep :biggrin: :hugs:
Reply 10
one-tailed are directional ie That like football more than girls.
two tailed are not directional ie There is a difference in which gender likes football more
Other words that you have nt stated which gender will like football more
Original post by la trampa
for a 1 tailed test you already know the outcome so basically your hypothesis is:
'x causes/affects/has something to do with y'. It's definitive.

For a 2 tailed test,you're not sure what will happen so your hypothesis is:
'we are testing to find out whether x affects/causes/has something to do with y'

in both cases your null hypothesis is that ' there is no relationship between x and y'.

:smile:


thank you for this!