Tagged Questions
1
vote
1answer
17 views
Insignificant block effect in two-way block design
I used a two-way ANOVA to analyze data collected in a randomized complete block design:
Y~Treatment+Block, where blocks represented spatial units
Whereas Treatment had a significant effect on Y, ...
0
votes
1answer
35 views
Simple Mixed Model with 1 Fixed and 1 Random Effect
I have various datasets I need to analyse regarding soil properties, all in the same fashion, with one fixed effect (which is a position along a transect, indicating different land uses). Now my main ...
1
vote
0answers
41 views
Two-way anova with interaction term: what is the point of a post-hoc test?
I have a statistics interpretation question. I've recently performed a two-way anova to identify an interaction term between my categorical independent variables (genotype + temperature) that ...
3
votes
1answer
32 views
How to prove the number of distinct distributions in a group of distributions?
Let's say we had 5 distributions: A,B,C,D,E.
An ANOVA test would tell us whether or not all of the means are equal, and thus a low p-value would mean at least one of the means is unlikely to be ...
0
votes
0answers
29 views
What kind of statistical analysis to use for a homework paper? Anova?
I am writing a paper where I have to pretend to have conducted an experiment. Each of the experimental groups and control has different people.
There are 8 experimental groups and 1 control.
1a 1b ...
0
votes
0answers
26 views
Calculating differences between groups and across time (age)
Let's say I have data of one variable $V$ measured for two groups of individuals ($a$ and $b$) and I want to see whether there is a significant difference between them and over time, i.e. $V_a$ stays ...
1
vote
0answers
61 views
Expected value of sums of squares of a blocking factor in a split plot design
How can we show that in a split plot design, the expected value of the sum-of-squares of the blocking factor has expected value equal to $k\sigma^2_{\text{block}} + \sigma^2_{\text{error}}$?
I tried ...
1
vote
1answer
57 views
How to interpret a non significant independent variable?
I conducted a regression analysis using R's lm() function. One of the independent variables shows no significance (p = 0.89), which contradicts the hypothesis that is should have a significantly ...
0
votes
1answer
27 views
Validation for ANOVA question
Can someone help me validate my answer to this question:
My answers come from the first row, where the significances are 0.0002,0.0011, and 0.0005, respectively. Since they are all below 5%, then ...
0
votes
1answer
54 views
Testing for differences, would I use ANOVA?
I have four age groups all measuring different heights: How would I test for difference between the groups at 0.01 level of significance? Would I use ANOVA?
Also - how could I establish which group ...
2
votes
0answers
77 views
Can I trust the result of a one-way ANOVA with many treatments each with very few replicates
I am doing a one-way ANOVA of a response variable (Y) on a treatment factor (T) of 7 levels. However, for each treatment, I have only 2 observations (or replicates). The ANOVA result shows the the ...
0
votes
1answer
81 views
Comparing means of three groups
When I want to compare the means between two groups I use a t-test.
But how do I check whether the means of three groups are equal or statistically different?
E.g. compare the average labour ...
0
votes
0answers
42 views
How to estimate the out crosses rate in crops?
How to estimate the out crosses rate in crops?
in have experiment included; main plot (1- seeds from open field 2- seeds from free pollinators cage 3-seeds from pollinator cage), sub plot (5 ...
6
votes
0answers
96 views
Estimating comparative success of different brochures
The Real World Problem
One of my clients is preparing to send a direct mailer to their subscribed user list, and this statistical challenge came up.
Their marketing team has 3 different brochures, ...
0
votes
1answer
61 views
Scientific way to show significance / test hypothesis
I am writing a report to show my results where, if there are more than 3 consecutive English character in a term, that term is noise. For example, "wooooh", "Noooo", etc. I have collected 100 sample ...
5
votes
2answers
370 views
Analysis of variance not statistically significant… but is there still a pattern to the data?
Problem I have a computer algorithm, and am attempting to measure the affect of a parameter (NS) on the output of the algorithm (SC). My hypothesis is that if the level of NS is lowered, there should ...
0
votes
0answers
155 views
Comparing the results of one-way-ANOVA and two-way-ANOVA
I don't know how to interpret the results of my one-way-ANOVA and two-way-ANOVA.
I have 2 independent variables (s.b.'s trust in the internet="v_563" and internet usage(frequency) = "v_614"). I ...
2
votes
2answers
452 views
Anova repeated measures is significant, but all the multiple comparisons with Bonferroni correction are not?
I counducted a mixed model ANOVA with time as the within subjects variable (3 levels) and group as the between subjects variable (2 levels).
All is significant (time, group, and timeXgroup).
To test ...
1
vote
1answer
90 views
Can lack of main effect and lack of interaction be caused by the same confound?
Can the lack of main effect have the same underlying cause as the lack of interaction in 2-way ANOVA?
My results failed to reach significance for variables of gender and language. Is it possible that ...
0
votes
1answer
393 views
What does it mean to have an F-value of .000 and Sig. of 1.000 (in SPSS)?
We conducted this very simple 2x2 Between Subjects Factorial Design Experiment, where the DV were their answers to a classic insight problem. Since there is only one correct answer to the problem, the ...
3
votes
0answers
180 views
Unfold degrees of freedom of interaction in factorial design analysis in R
I've been trying to analyse data from a factorial design with missing cells without much success until now. I'm using Anova from car package, that, according with I've read, can handle unbalanced data ...
1
vote
1answer
171 views
Using ANOVA and t-tests with pre-aggregated data
I have a set of experiments that I'd like to run some significance tests over. It looks like:
...
0
votes
0answers
308 views
How can I compare the effect of an pre-post intervention between two groups with multiple numeric dependent variables?
I have collected data from two groups (age 25-30, age 30+). In each group I have 10 patients. I performed several medical tests (i.e., R.B.C, Liver test, etc.) on the patients, before and after ...
3
votes
2answers
3k views
What if an overall ANOVA is not significant, but specific contrasts are?
Study Design: I have a 2x3 factorial design, 2 levels of Time (2050 or 2100) by 3 levels of information (None/Control, Moderate, Extreme).
I set up some very specific contrasts when analyzing this ...
0
votes
2answers
758 views
Statistical Significant Difference between 5 groups of data
I'm trying to compare 5 different gears used by fishermen and the amount of bycatch found in each. The values have a unit of "% of time encountered" and range between 0% (ie: never have bycatch) and ...
0
votes
1answer
1k views
What statistics should I use to compare percentages?
I am trying to see if there is a statistical significant difference between the amount of bycatch in 5 different types of gear used by fishermen. For each gear I have varying number of replicates as ...
0
votes
0answers
46 views
Can two RM ANOVAs be run including one variable that is the same but this variable only be significant in one of the ANOVAs? [duplicate]
Possible Duplicate:
Why ANOVA/Regression results change when controlling for another variable
I have used SPSS to run two RM two-way ANOVA with the same data.
RM ANOVA #1 has two within ...
2
votes
1answer
591 views
ANOVA in SAS: Not Statistically Significant but LSMEANS says is?
I'm running an ANOVA model. I found my model does not meet constant variance assumption and corrected for that using a weighted ANOVA model. I don't think that changes anything..
After I run the ...
5
votes
1answer
384 views
Is it permissible to run post-hoc tests after a non-significant ANOVA?
We ran a 3-way ANOVA getting a non-significant result, but in doing so we saw that one condition looked like it had a strong effect. We tried a Bonferroni-corrected t-test of just that group, and it ...
12
votes
1answer
41k views
How to interpret and report eta squared / partial eta squared in statistically significant and non-significant analyses?
I have data that has eta squared values and partial eta squared values calculated as a measure of effect size for group mean differences.
What is the difference between eta squared and partial eta ...
4
votes
2answers
285 views
Is significance more important than absolute value?
I have three groups and I'm comparing two graphs in each group using the t-test:
the absolute difference between two graphs in the first group is 34 with a p=0.024. (*)
The absolute difference in the ...
15
votes
2answers
2k views
Do we need a global test before post hoc tests?
I often hear that post hoc tests after an ANOVA can only be used if the ANOVA itself was significant. However, post hoc tests adjust p values to keep the global type I error rate at 5%, don't they? So ...
5
votes
1answer
2k views
Which non-parametric test can I use to identify significant interactions of independent variables?
I have an experiment producing results (dependent variables) that don't pass tests of normality, thus I am testing hypotheses using non-parametric tests.
My DVs are continuous, while my factors ...
2
votes
0answers
347 views
What is a good statistical test for independent replicates?
I have a series of measurements in which something is sampled and placed into either category 1 or category 2. I have 3x2x3 factors for each set of measurements, and each set of measurements is done ...
5
votes
2answers
562 views
How to fix the threshold for statistical validity of p-values produced by ANOVAs?
I have run experiments on a group of users under two conditions, measuring the time it took users to finish their experiments. I used a cross-over design where half of the users started in the first ...
4
votes
2answers
2k views
