Tagged Questions

39 views

How to exclude interaction effect in linear regression modelling?

I am working with biological dataset. I am looking for significantly differentially expressed genes that stand out under effect of 3 different factors (e.x. gut microbiota level has/not, tissue, ...
27 views

Experimental design type?

A pencil depth tester is used for various pieces of paper. Two different pencils are used. The class measures how deep the pencils go into the various pieces of paper. Paper Pencil Depth ...
94 views

What is the most appropriate test for a multi-year different group/yr experiment?

I've been working on a research project for close to five years now. For my thesis I have to show how "well" did my approach improve things. Setup: Every year we use a tool A to brainstorm and ...
68 views

Experiment design question

I have a naive question about experiment design (I am not a statistician by trade). Suppose I am doing social psychology, and I am setting up an experiment like Milgram's in the sixties. Do I really ...
96 views

2x2 factorial design minimal expected significant factors

I'm at the point of conducting a 2x2 factorial design. My adviser says that it has no use to conduct an experiment based on such a simple design unless you expect everything to be significant; 2 main ...
62 views

How to analyze data from a 2x3 experiment where one cell is missing?

I have an experiment with two factors. The first factor, picture, has three levels: nice, ugly, absent (i.e., the picture is not presented). The second factor, information, has two levels: present, ...
135 views

The result of absolute change and relative change in t test is different

My task is to evaluate the effectiveness of an intervention. In my study, there are one control group and one intervention group. There are two time points, baseline and endpoint. And I use the score ...
160 views

Bioinformatical problem - specific word enrichment in a given sequence

My bioinformatical problem looks like this: two sets of gene sequences (size of set A > 1000, size of set B > 1000; sequence length varies from 1000 to 100000). Set_A_Sequence_1: ACGTACGTACGT... ...
50 views

Evaluating if the new process was better than the previous?

Initially things were done in a particular way (A) and I changed to in some key ways to do things a bit differently (B). Now I wish to evaluate whether the change was for the better. What tests can I ...
55 views

How to rank order performance of four systems using aggregates of pairwise assessments of system performance?

I am currently designing an experiment to evaluate 4 iterations of a system. As it is rather difficult for a human to judge the output of the system by assigning it a score or several scores, I plan ...
87 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 ...
174 views

Compare means of two groups with a variable that has multiple sub-group

I was unable to understand how to compare multiple mean values in each group. Within the subgroup the mean values influence each other (If one changes, the other changes automatically). I collected ...
85 views

Determine if a statistically significant preference exists

I'm trying to determine if there is any statistically significant preference for objects (other content, products, etc) rendered in a module in a web page. I'm trying to create a simple experiment to ...
416 views

Testing statistical significance of male vs female enrolment preference percentages between two different fields of education

The problem I have is as follows. I have enrolment data describing the number of male and female preferences for two broad fields of education: i) Information Technology and ii) Engineering. The ...
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I'm running a marketing test comparing banner A against banner B against banner C. Each banner received >10million exposures and based on response rate we concluded early in the test that banners B ...
235 views

What if your randomly formed groups are clearly not similar?

What if, before you begin the data collection for an experiment, you randomly divide your subject pool into two (or more) groups. Before implementing the experimental manipulation you notice the ...
128 views

Limitation on group size with non-parametric permutation tests

I would like to know if there is any limitation in the size of the groups when you are implementing non-parametric permutation tests. My case belongs to the realm of medical imaging. I am comparing ...
105 views

I have two questions on interpreting the statistical analysis of data collected from production runs to produce an experimental material. We made four production runs, with some changes in each run. ...
399 views

Analysing data from non-equivalent groups in a quasi-experimental design

I am doing a research on two groups, one experimental and one control, which are not randomly selected. In fact the two groups are intact groups. The purpose is to find the effect of the number of ...
741 views

Calculate number of needed simulations

First I have to apologize for any uncorrect naming or categorisation of my question, as I am an electrical engineer rather than a mathematican. I have a simulation that outputs for a given number of ...
255 views

How to deal with a 2x2 experimental design if the dependent variable is dichotomous?

I am assessing the acceptability of a sentence in a within-subjects design with two crossed factors (type of sentence, missing word). After reading each sentence, the participants answer a simple ...
320 views

Why is running split tests until statistically significant a “bad thing”? (Or is it?)

I read this article on "how not to run an A/B test". And I still don't understand what exactly the author's reasoning is. Can someone dumb it down for me? I think what it might be saying is that ...
160 views

How to compare results from two groups?

I'm getting confused with the analysis of one of my experiments. Here is how the results look like. There were P participants in the experiments and they were split into two groups P1 and P2. Every ...
118 views

Can someone help me understand what type of problem I am looking at? Not sure if this classifies as hypothesis-testing

Please pardon me if this question is not clear. I am not sure if I am using the right terminologies. I have conducted an experiment in different environments multiple times. So my data looks ...