Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [fishers-lsd]

Fisher's LSD is a method to compare multiple group means following a significant ANOVA.

Fisher's LSD is a method to compare multiple group means. Following a significant ANOVA, pairwise t-tests are conducted using the pooled SD from the ANOVA. It does not control for familywise type I error.

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Is Fisher's LSD as bad as they say it is?

When we perform experiments (on small sample sizes (usually the sample size per treatment group is about 7~8)) on two groups, we use a t-test to test for difference. However, when we perform an ANOVA (obviously for more than two groups), we use…
Rover Eye
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Reject $H_0: \mu_1 = \mu_2 = \mu_3$ but not $H_0: \mu_1 = \mu_2, H_0: \mu_3 = \mu_2,$ or $H_0: \mu_1 = \mu_3$?

Is it possible to reject $$H_0\!: \mu_1 = \mu_2 = \mu_3,$$ for example, with an F test in the context of an ANOVA table, but not reject any of the following: \begin{align} H_0\!: \mu_1 &= \mu_2 \\ H_0\!: \mu_3 &= \mu_2 \\ H_0\!: \mu_1 &=…
BCLC
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Post Hoc test: Fisher LSD or pairwise two sample t.tests

A Fisher LSD test is basically a series of pairwise t-test except that the pooled variance is computed on all groups (and therefore does not vary from one comparison to another) while the normal t-tests calculate the pooled variance on only the two…
Remi.b
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lsmeans multiple comparisons and Fishers LSD

I am using the lsmeans package for "post hoc" multiple comparisons and I read here: ANOVA - Do we need a global test before post hoc tests? that in general post hoc tests are valid even if the ANOVA result is not significant. The only exception is…
Pharcyde
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FIsher's LSD test is appropriate for restricted mean comparisons

Suppose that we perform two way ANOVA with interactions, with factors $A$ and $B$ with three level each $A_{1},A_{2},A_{3}$ and $B_{1},B_{2},B_{3}$. We know that Fisher's LSD test is used for comparing means. The most common hypothesis for Fishers…
G1I2A
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Can Fisher's LSD fail to identify difference when the overall ANOVA test rejects?

I understand that Fisher's LSD test is used as a post hoc analysis if the ANOVA test rejects the null hypothesis All the means $X_1, X_2,.. X_n$ taken from various samples are equal. Also, given that if we reject null hypothesis via ANOVA, we can…
honeybadger
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Combining One-way ANOVA followed by Fishers LSD and unpaired ttests?

I am analysing data on levels of proteins in the brain, there are 4 groups, I did a one way anova followed by Fishers LSD. I also carried out individual unpaired ttests comparing each group to the control. For some of the groups I got a more…
Emma
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How can I obtain degrees of freedom of LSD test that give Inf?

I am performing a LSD test after getting GLMM results. My goal is to know the differences between classes (in this case the difference between grinding methods, I assayed III methods). The GLMM output obtained was called "glmer.conc.Grinding_Kit".…
Adrián P.L.
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Confidence interval calculations Tukeys vs Bonferroni vs Fishers LSD?

I am trying to work out how the Confidence interval calculations for the Tukey, Bonferroni and Fishers LSD differ and/or are similar from each other? From my understanding they all consider the standard deviation of the sample groups, number of…
WrangleStack
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ANOVA and LSD grouping in R when mean and variance is given

I have the following data. Strain n mean variance A 8 75 18 B 8 70 23 C 8 72 21 D 8 78 20 I want to calculate their ANOVA and LSD grouping in R. I know the simple way…
Mendel
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How to determine significant difference between treatments

What statistical method would you apply to determine if treatments are statistically different. For one treatment I have 26 samples all with 4 measurements. Those measurements are then averaged for each sample and then added for a total value. …
Barb
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What are the drawbacks and benefits for the Bonferroni Adjustment, Fisher's LSD, and Tukey's HSD procedures?

When do you use which test and which test is best for isolating the differences in multiple comparisons?
user5943954
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Biochemistry table interpretation help!

I have a table that uses the Fisher LSD and has significance "in each column". I'm having trouble interpreting it. Is the significance just for that individual column or can they compare to other columns? I know the superscripts are difficult to…
teach2md
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Tukey's Test or LSD Fisher

I'm trying to solve the above exercise, but my question begins with which test should I choose: Tukey test or Fisher's LSD? I read several things and still can not tell the difference between the two when it is preferable to use each other?
user72621
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Fisher's LSD test

When we calculate Fisher's LSD test, why do we use Mean Square of Error which is the variance of all groups (pooled variance), as a variance of each individual group mean? In the denominator it's: sqrt(MSE/n1+ MSE/n2). Why don't we use group…
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