All Questions
438 questions
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31
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How do I do significance testing in this experiment?
We have an internal search engine system similar to google. On a default config A, if we give a query, it will give 1000 results with a rank. If the same query was given again, it will again give 1000 ...
0
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0
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21
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statistical test for paired data with different treatments (ANCOVA? ANOVA? paired difference t-test?)
I have data like this (the data is made up):
...
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1
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0
answers
35
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Fixed-sample size sequential ANOVA or t-test
I have an experiment of fixed sample size where units (20 in each of 2 or 3 arms) are allowed to grow over time. I wish to stop the experiment as soon as there's enough evidence that the arms do not ...
- 1,129
0
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0
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25
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Post-hoc tests or multiple-corrected t-tests? [duplicate]
I am interested in the changes compared to the baseline in a specific gene, across about 15 timepoints (with 3 samples per each time point).
Besides plotting, I could calculate 15 t-tests and perform ...
- 777
1
vote
1
answer
54
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Two way anova or paired t-tests
i am looking to see if there is a difference in dissolved oxygen levels between pool surface (S) and bottom (B) samples at four sites (an up and downstream site in two creeks). There are 3 replicate ...
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2
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2
answers
31
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One way ANOVA on compliance rates (by time period) with different lengths
I'm stumped a little on this, as in my stats classes we had very nicely packaged data with nice, normal data that was easy to understand! Apologies if this seems totally obvious.
My data is a series ...
- 21
8
votes
6
answers
759
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Is it better to perform multiple paired t-test or One-Way ANOVA test
I have 7 patients with blood measurements from two different tissues and at two different oxygenation states. We first took measurements from tissue A and B (Normoxia) and then we administrated oxygen ...
- 201
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22
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In a 2 arm pre-post RCT, is an interaction test on an ANOVA the same as a t-test of the change scores?
Say you have a 2-armed pre-test post-test control trial design. You want to test the effect of group allocation on the outcome variable. I simulated a version of this in R, using 3 different methods: ...
1
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1
answer
47
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How do I do the p-adjustement in statistical tests?
context: a study about which type of bread and/or filling attracts ants the most
I have a table with 3 columns : the number of ants attracted, type of bread, type of filling. The question is : do ...
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1
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49
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How to easily convert frequency data into raw data (large dataset) for t-test? [closed]
Statistics goal: Determine if the difference between two datasets is statistically significant.
Dataset description: The data is available in the form of particle size (mm) v. particle count (...
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37
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Is it possible to conduct an F test without fitting a restricted model?
Say I'm fitting the following regression:
$$
Y = \beta_0 + \beta_1X_1 + \beta_2X_2 + \beta_3X_3 + \beta_4X_4
$$
If I was interested in testing the hypothesis that $\beta_2 = 0$, I know I can do things:...
- 21
0
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0
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23
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Relationship between f test and t -test [duplicate]
I am working on a problem where I should derive the t test statistic from an f test given an ANOVA table (below). From my understanding, when we conduct an f-test we are using the variance to ...
- 345
2
votes
1
answer
19
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selecting the most appropriate statistical test for comparison of multiple independent variables belonging to two groups
I want to compare the drinking water chemistry of two areas. A disease is prevalent in one area while the other area is almost free from this disease. I have measured the concentrations of 10 ...
0
votes
1
answer
59
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Does a 2x2 study mean there are 4 groups or 2?
My study is a 2x2 design.
There are 2 IVs:
IV1 = sex (m/f) ;
IV2 = control / experimental groups.
Does this mean that I have 2 groups, and will therefore be using an independent T-Test, or i have 4 ...
0
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1
answer
44
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Test for significant difference between two groups measured across time
I have two groups of time-dependent samples whose measured value changes nonlinearly with time. There are 3 samples in group A and 3 samples in group B. An example of my data is illustrated below.
...
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0
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0
answers
26
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How to do ANOVA/post-hoc analysis when 'control' is used to normalise the data?
I am analysing the transportation rate for a number of different mutants in a particular transportation system. I want to know how I can perform statistical tests on this data in a valid way, given ...
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1
vote
1
answer
66
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What if anything is being fit in a one-sample t-test?
I am revisiting some basic concepts involving t-tests and ANOVAs, and got tripped up early. I wanted to apply the concept of lack-of-fit sum of squares to the single sample t-test but wonder how this ...
- 165
0
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0
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31
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F-statistics and paired t-test
I want to create a synthetic data set with $n = 3$ replicates for each of $a = 3$ groups such that
the overall F - test rejects $H_0: µ_1 = µ_2 = µ_3$ at the $\alpha = 0.05$ level,
but all three ...
- 1
2
votes
1
answer
31
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Can ANOVAs or Student tests be conducted on any summary statistic at the individual level?
I am wondering if ANOVAs or Student tests can be performed on any summary statistic of performance at the individual level without any effect on type 1 and type 2 error.
For example, consider a simple ...
- 191
0
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0
answers
68
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One-Way ANOVA for two groups VS. t test
When comparing 2 groups (K=2), we can either perform a t-test or f-test of One-Way ANOVA, because the f-test is equal the t-test squared(t^2 = f), it essentially goves the same resilt, right ?
Only ...
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2
votes
1
answer
54
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Compute ANOVA F if you only know post-hoc results
It's not uncommon to read a scientific article in which the authors perform an ANOVA followed by post-hoc t-tests, but don't report the results of the ANOVA at all, and instead skip straight into the ...
- 1,944
0
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0
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11
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One-sided tests [duplicate]
I use a statistical program that does not seem to offer the option of conducting t-tests, ANOVA, etc as one-sided tests. Only a 2-sided p-value is returned. Is it equally valid to arrive at a one-...
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2
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1
answer
126
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Statistical test for a biology experiment when plants were grown in 3 different solution concentrations
I have conducted an experiment for my Biology Internal Assessment in the IB Diploma Course where I grew Phaseolus coccineus beans for 14 days. This is the overview of my experiment:
Independent ...
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0
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1
answer
37
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T test or a different analysis? advice
I want to make sure i get the right analysis.
I have taken chemical measurements of soil at two grasslands at two depths. For example soil PH.
So one with chemical treatment and one without at two ...
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2
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1
answer
32
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Use of simple statistics for matched study designs
This might be a silly question, but I have always found this confusing. In a case-control study one selects participants to the study based on having or not having the outcome, in addition to some set ...
- 445
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1
answer
73
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Robustness - Independent samples t-test vs. One-Way ANOVA
I am trying to compare the means of two groups (male/female) for different attitudes. Since my data sometimes violate the assumptions of normality and heteroscedasticity, I was planning to do a Mann-...
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1
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32
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Which averages in a set are probably identical
Suppose there are $N$ types of blocks. The blocks are labelled with their types. The average weights of the types are in the set $\{w_i\,|\,\,i<N\}$. In other words, at least one pair of block ...
- 153
0
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1
answer
21
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Correlation / Regression: Best way to analyse factors that influence purchase intention
I am working on my dissertation and am stuck with the data analysis section.
Topic: Luxury Fashion Influencers on Instagram: The impact of source and content factors on Gen Y and Z followers' purchase ...
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0
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40
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Advice on which statistical tests to perform in this scenario
I am trying to perform a couple of statistical tests to determine significance from categorical variables (e.g., treatment, station)
The experiment is microcosms with freshwater amended 2 different ...
1
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1
answer
190
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How to analyse reaction times in SPSS?
I've learnt basic stats but I'm a bit confused on how I should so this, I'm gonna try and explain it as best as I could.
So I had participants doing a driving simulation which includes two different ...
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2
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2
answers
230
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For 2-way ANOVA data, if I have already use t-test which suggested no significance between any pair of groups, do I need to perform ANOVA?
If I have two factors - 'A' and 'B'. Each factor has three levels (A1,A2,A3,B1,B2,B3). If I have already performed t-test for each pair such as (A1,A2). All result suggest no significant difference. ...
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0
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0
answers
30
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Appropriate statistical tests (hypotheses) for categorical and numeric values on a specific dataset in R
I am new to statistics and I was hoping someone could guide me on what statistical tests I should complete in R on the following dataset. I am trying to investigate the relationship between births and ...
2
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0
answers
22
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Necessary to transform ratios for ANOVA and T-Test?
I am using ANOVA and T-Test to compare wheat grain characteristics between states, agroecological zones, soils, etc.
Most of this data is grain mineral concentrations but some of it is ratios ...
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0
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1
answer
144
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Planned contrast in 2x2 factorial design
If there are only 2 groups for each manipulation (2x2 factorial design), how can you do planned contrast or post-hoc analysis comparing between two specific groups? Do you just do t-test?
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0
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18
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Measuring before and after results of a treatment with N people and K trials per person
Let's say I have a group of 10 students and I want to study the effect of a treatment on their memory.
I will have them each take 20 indistinguishable memory tests. Then I will administer the ...
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2
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0
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14
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Which test is most appropriate?
My experiment had 3 tubs, each containing the same substrate. I grew maggots in the substrate of each tub.
Once mature, 3 samples of these maggots were harvested from each tub giving me 9 subjects.
...
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0
votes
1
answer
375
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Multiple paired t-tests or repeated measures ANOVA in one group?
I have read up on a number of threads discussing this, but none address my exact situation so I thought I would try my luck with outlining what I'm working with and getting more relevant insight.
I am ...
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0
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0
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37
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Which stats test should I use?
I have a dependent variable which is tree cover loss and independent variable which is temperature. Both variables have 20 groups/regions in a country in them and I want to do some kind of stats test/...
1
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1
answer
1k
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Repeated measure design with missing values
I have data from a repeated measure design, as follow:
Each subject is measured under 10 differente experimental conditions
For each experimental conditions, 2 physiological caractéristics are ...
- 171
1
vote
0
answers
25
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Which statistical test use for comparing selection differences in three different conditions?
In an experiment, I wanted to check the effect of image redness on subjects' choices of an image. I modified the images at three redness levels (I: Increased redness, N: Normal, and D: Decreased ...
- 111
1
vote
1
answer
1k
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Three treatment groups vs one control group - only interested in comparing each treatment group separately to control - best test/follow-up test? [duplicate]
I have an analysis in which I have three treatment groups each assigned to a (different) experimental condition, and one group assigned to a control condition. I am interested in whether any/each of ...
0
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1
answer
38
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ANOVA or T Test and the assumptions in Paper
I have a question regarding how to use ANOVA appropriately in my paper. The following is my sample data.
The mice are randomly selected. The first row is the control group as health mice. There are ...
0
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1
answer
61
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Would I use a one-tailed paired-sample t- test on this?
I am doing an assignment that tests whether acceptance and commitment therapy is beneficial for social anxiety disorder.
With an experimental and controlled group.
I just need to know what test I ...
1
vote
2
answers
69
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Ecological study with pseudoreplication, should I use t.tests with bonferonni correction or a repeated measures ANOVA?
I have a study where I will treat two ponds and measure changes in soil texture. I only have access to the two ponds, but will collect soil at 15 points in each pond. One pond will be flooded and ...
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0
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0
answers
19
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Type of test for control and 3 variants or treatments
if I was thinking to design test for a control and 3 treatments or variants looking at a 0 dollar value for control and then 5,10 and 15 dollar amounts for completing an assignment, would a normal t-...
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1
vote
1
answer
48
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Calculating an effect of intervention on two groups with very different values
Imagine I run a marketing campaign in two cities with very different number of citizens (like A: 1000 and B: 1000 000).
Purchases_A and Purchases_B define the number of products sold in each city:
<...
- 133
1
vote
1
answer
275
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Understanding estimates of qualitative supplementary variables by dimdesc() of FactoMineR package
FactoMineR package is helpful when doing PCA and much more. Coming across the output using dimdesc() function and looking at the estimates of supplementary ...
- 1,147
1
vote
1
answer
220
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Bonferroni (or BH) correction for multiple t-test?
I'm studying the kinematics differences between males and females examined at two different specific walking speeds (slow/fast). Specifically, I'm exploring:
a) slow speed vs high speed (dependent t-...
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1
vote
1
answer
74
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Comparing sample fluorescence at different temperatures
First of all, sorry if this format of question has already been answered - but I've had a look at previous answers and still can't figure this out for the life of me.
So, I have these 15 samples of ...
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4
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1
answer
123
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Three versions of the independent two sample t-test (and R)
This post concerns three versions of the independent two sample t-test:
Student's t-test uses a pooled standard deviation in the denominator (all equations are shamelessly copied from Wikipedia - ...
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