T Tests

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what are the requirements of a T-Test?
data must be scale at an ordinal or nominal level, there must be a normal distribution, there must be similar variance, there should be 2 variables and replicates sampled from each treatments are independant of eachother
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What goes on the X and Y axis of a t-test?
Y=scale (response) X= ordinal/nominal (treatments)
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what does the P value measure?
how well the H0 describes the data, the level of interesting vs uninteresting data. Lower is better.
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what is the equation for mean?
x=(sumE)n1 xi/n
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what is the equation for standard error?
se=s/ (square root)[n
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what is the equation for t test?
t=x1-x2 (interesting)/ sx1-x2 (uninteresting)
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what is the equation for sx1-x2?
sx1-x2=root of: (s2p/n1) + (s2p/n2) s2p=pooled variance n=sample size
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when to used 1 and 2 tailed t tests?
a one tailed t test is when data is directinal so you know one is bigger than the other a two tailed t test is when the data is none directional so one could be either bigger or smaller than the other
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which (one or two tailed) do you use if you are unsure and why?
you use a two tailed t test becuase it is more conservative, a 1 tailed t test divides the P value in half becuase the direction is known
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when does the P value become large?
when the difference between the samples (x1-x2) is large, the standard error is small (sx1-x2) and this is caused by a very small sample size (se=s/[n)
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when to usea two sample t test?
when you are comparing two samples eg/ height of two groups of people
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when to use a one sample t test?
when comparing one against a known value eg/height of a group against a known height
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when to use a paired sample t test?
when you are comparing a series of pairs eg/ size of left and right arms
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Other cards in this set

Card 2

Front

What goes on the X and Y axis of a t-test?

Back

Y=scale (response) X= ordinal/nominal (treatments)

Card 3

Front

what does the P value measure?

Back

Preview of the front of card 3

Card 4

Front

what is the equation for mean?

Back

Preview of the front of card 4

Card 5

Front

what is the equation for standard error?

Back

Preview of the front of card 5
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