All Questions
438 questions
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Is it possible to compare means of pre & post intervention questionnaire for only 3 participants?
I am completing my dissertation which was to determine if a 6-week expressive writing intervention would reduce aggressive behaviors & increase emotion regulation in students. My first variable (...
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0
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0
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15
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Can I use one-way ANOVA for two and for three groups in order to maintain consistency across different sample types?
TLDR: Some of my larger dataset has two levels, while some has three levels. Is it appropriate to test everything using one-way ANOVAs or should I do some as t-tests and some as ANOVAs (Welch's for ...
0
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0
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138
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Which Hypothesis Test for AB test with 4 variants
Disclosure: Stat noob trying to understand the basics of ab testing
Context: I'm running an AB test with 3 treatment test to see which one yields the highest click thru rate.
Q: What is the recommend ...
- 211
1
vote
1
answer
153
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Compare variance across time
I have an analysis question. Unfortunately my biostats collaborator is no longer involved in the project.
We have a dataset of n=6 people. the study was terminated early due to covid but we are still ...
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1
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1
answer
460
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Shapiro Wilk test of normality
I ran my data under JASP and the p-value for the shapiro wilk test of normality was <.001. How do I interpret this?
- 11
0
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1
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793
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Comparing pre-test post-test results t-test normal distribution
Is the best way to compare the intervention group (n=32) with the control group (n=32) to do a t-test? I've got pre-test and post-test results and did t-test of both the pre-scores (IG compared to CG) ...
0
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0
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54
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Hypothesis test for classification model
I have a model that outputs 0 or 1 for interest/not-interest in a job. I'm doing an A/B/C test comparing two models (treatment groups) and none (control group).
ANOVA for hypothesis testing and t-test ...
- 1,087
1
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1
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112
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Which test is suitable for such data? t-test, ANOVA, linear regression?
I have data in the following format:
Concentration
speed
height
distance
control
1.5
3.1
13.1
0.1
1.9
5.4
13.5
0.2
2.3
9
16.7
0.4
2.7
13.1
21.2
I am confused as to what test I should use to see ...
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0
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48
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I’m trying to find the association between 2 variables by conducting a statistical test
My two variables are sex (male/female) and body mass index (BMI). I have a data set of 194 participants.
Sex - 107 males (55.15%) / 87 females (44.85%)
BMI - 23.88 +/- 5.03
I have no idea which test ...
1
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0
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158
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T-test with replicate measurements, how to quantify error in the measurements?
I want to compare two tools, A and B.
I use tool A to measure 10 very different objects, making 5 repeated measurements for each object so I can record an accurate value.
I also do this with tool B.
...
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1
vote
1
answer
238
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low sample size experimental design, t-test vs one way ANOVA
I'm designing a biological experiment wherein the sample size is very limited, as each sample is very hard to get. Moreover, I need to have 4 independent groups, each receiving a different treatment.
...
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1
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0
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36
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Suggestion Needed about Design Experiment
As a part of my coursework, I'm supposed to be designing an experiment for an online cab service provider to understand the following:
Whether letting the cab driver know the drop location of the ...
- 123
1
vote
2
answers
401
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t-test with data in long-format including levels of non-interesting factor in R
I've computed an ANOVA with one between-subjects factor (2 groups each including 26 participants) and 2 within-subjects factors (item type with 3 levels and emotion with 2 levels) in ezANOVA. ...
- 45
2
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1
answer
1k
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Equal Variance vs. unequal Variance for comparing Groups
I am a little bit confused about equal and unequal variances. I understand the definition and mathematics behind it, yet I don't know, for the purpose of my research, how to appropriately test that.
...
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11
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3
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4k
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Is this p-hacking?
I'm currently looking into the gender pay gap using data from glass door (found via kaggle). The dataset has columns for gender, age, performance evaluations of employees, seniority, pay etc.
For ...
- 315
-1
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1
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45
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Is there a way to check for the good amount of replicates for let's say T test or just mere One-Way anova (a priori)?
I have already asked this in Reddit but I really cannot find the answer
I know you can check for amount of sample sizes in G power but not really for experiments.
I can't be using a minimum of 100 ...
- 39
0
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1
answer
2k
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Why does using t-test on multiple groups of means will increase the alpha of the test?
I saw a video about ANOVA today.
It said that we should use ANOVA instead of t-test when we have more than 2 groups of sample to test.
This is because if we us t-test instead of ANOVA, it will be ...
- 111
1
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0
answers
14
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Comparing means--some scores within, some across groups
I have a pool of scores. In my design, two groups of subjects complete either experimental task A and a control task, or experimental task B and a control task (the same kind of control task as other ...
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0
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0
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69
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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 ...
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1
answer
19
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How to use a one sided test case to find which primer pairs are best?
I am assessing which potential primer pairs are good among 6 primer pairs (pairs p1 to p6). The criterion is that a good primer pair should amplify DNA at minimum 1.95 times every cycle (1.95 fold ...
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2
votes
1
answer
590
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Which type of statistical test should I use for categorical and continuous IVs and continuous DV?
I am conducting an experimental research. Research model shown as figure.
I hypothesized that X positively predicts Y. All participants were required to answer measurements of X and Y.
Meanwhile, ...
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0
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1
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74
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Best statistical approach for psychological experiment
I have done an experiment where I have two groups of patients that received different treatments (Group1 received treatment 1, Group 2 received treatment 2). I measured a value that should be ...
user342084
0
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0
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35
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paired t-test for two different samples and measurements taken in two different years
I measured hourly temperatures of site A and site B in June 2016 and June 2017. I used paired t-test to compare the means of site A & B for June 2016 (n=720) and p-value was 0.07 (significance ...
- 1
0
votes
1
answer
166
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Help understanding Anova Three Factors
I am looking to understand the following table from this article to better understand some statistical stuff.
The article is exploring the outcomes of meat via 3 factors(marinade, temperature and ...
- 135
1
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0
answers
76
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Need to run Bonferroni correction if only doing 1 paired-samples t-test?
Say I have a significant interaction for a 2x3 within-subjects ANOVA. If I have a theoretical justification for only running a single paired samples t-test to look at simple main effects (even when ...
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1
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2
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2k
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Statistical test to compare means when I have two observations per group?
I am trying to interpret the results of my experiment but am not sure what statistical method I should choose. For my experiment, I added 3 types of different fertilizers to soil, with a control, and ...
- 143
3
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2
answers
759
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Statistical significance test of kurtosis differences
I would like to raise a problem that bothers me. However, I would like to point out right away that my question is purely theoretical, and the data presented here comes only from a computer experiment ...
- 160
3
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2
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19k
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Best statistical test to compare two groups when they have different distributions
I am teaching myself to use and apply statistics to a big database.
I have 2 groups that I wish to compare, healty controls (HC) and patients (P).
The sizes are HC= 84, P= 196.
Each group has many ...
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3
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1
answer
2k
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What to do with outliers? Should you use capping, remove outliers, or use non-parametric tests?
This will be my first question on Cross Validated, and besides, no one has ever taught me statistics. I am completely self-taught in this regard. So please forgive me if my question seems trivial.
I ...
- 160
1
vote
1
answer
54
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Comparing Means of 2 Groups of Different Sizes Across Time
I am trying to figure out the correct test to compare two different groups between two-time points.
I will have a baseline data collection of the stress levels of male and female caregivers and a ...
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1
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1
answer
22
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Should I use an ANCOVA test?
For this data set:
I want to see if the DNA levels differ if there is food or no food and if this changes due to the number of days.
Does it make sense to use ANCOVA as the Age could be considered a ...
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0
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1
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33
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Does two way ANOVA excludes depending of one of the factors?
I am not statistician so I am sorry if my question formulation sounds confusing.
The ultimate goal is to comapre two methods (A and B). Each method creates 24 numbers (so, 24 pairs). Apart from the ...
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1
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280
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How to analyze the effects of two treatments on two groups as measured by pre, post, and delayed post tests?
I taught two different classes using two different teaching approaches. Each class was given pre-test, immediate post-test, and delayed post-tests to assess their understanding of the topic. The pre-...
2
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1
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98
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pretest-posttest experimental design: which anaysis tests to use?
I am new to this website, and I hope to find help. I am writing my MSc thesis on phishing education.
I have three groups and use pretest-posttest experimental design
Control
Training 1
Training 2
It ...
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1
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1
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31
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Which test can I use for this science related project?
I’m currently doing a science project on sickle cell disease, I’m researching to see how a well a few drugs can induce fetal haemoglobin in sickle cell disease patients.
Currently what I’ve done is ...
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1
vote
1
answer
521
views
Repeated measures ANOVA / paired t-test on different sample sizes
I have multiple subjects walking under three experimental conditions to investigate how the step lengths are affected. Each subject performed all three conditions but the number of steps recorded is ...
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0
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0
answers
85
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What statistical test should be used when measuring mean difference between two groups over 3 time points?
I have a study that I am having trouble defining. I have two independent groups that I would like to measure various features to see if they are significantly different between each other. The two ...
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1
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2
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986
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What statistical test is appropriate for a pretest/posttest experimental/control group study?
I thought this would be a relatively straightforward question, but I'm having difficulty finding a decisive answer. Let's say I'm planning to run a study to test the effectiveness of a new type of ...
0
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1
answer
49
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how can I compare if a drug affects a biological process differently than vehicle treatment
I have an experiment where I am trying to see if a drug has a biological effect that is significantly different from vehicle. Activity is measured before and after treatment.
For treatment, I have ...
2
votes
1
answer
110
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Robust linear regression for group differences
I am trying to understand what it means when a p value for a grouping variable is < 0.05 after running robust linear regression.
Does this mean that the 2 groups significantly differ with respect ...
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2
votes
1
answer
106
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What statistical test would I use with 2 groups and a control to show significant difference?
Question I would like to answer: To encourage more referrals, the product team is running an experiment on the iOS app, called “ios_referral_experiment”, that tests adding new links to the referral ...
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0
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1
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55
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Which significance test is the best for measuring the response to two survey questions are significantly different?
I have a survey where there are two questions designed in a Likert Scale (1-7). Let's say:
Q1: Your ratings for apples.
Q2: Your ratings for pears.
By counting the frequency of the likert response. I ...
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0
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0
answers
13
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Need help on running sample data analysis -
Background: I have a survey data for a year 2019 where I received 50% response rate. I wanted to compare it with 2020 data which has 65% response rate. Question being asked in the survey is to rate ...
0
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1
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44
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I need to run a comparison test of mean biomass of species between 2 different locations. Problem - too many zero values for my dependent variable
I need to run a t-test and series of ANOVA tests (through SPSS, excel, or Matlab) to compare the biomass of 20 species (dependent variable) found at 2-4 different locations (independent variable).
The ...
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1
vote
1
answer
47
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$2$-step (paired) t-test - or what?
Today I was asked about the following variant of a testing-question, and the proposal by the asker was a modification of a t-test, but I'm not sure about this.
The situation is as follows:
there is a ...
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6
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6
answers
5k
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Comparing two, or more, independent paired t-tests
Can we compare the results from two, or more, independent paired t-tests?
For example: I want to test if drug 1 and drug 2 are effective to reduce weight. I have a control group (that will consume a ...
- 217
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0
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28
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What is the best test for comparing two means of unknown size and standard deviation?
I need to compare a series of means for two unequal student groups (A & B) and need help identifying which test is best to use. I do not have access to the entire data set, just summary ...
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1
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0
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162
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Testing whether means of several gamma distributions are equal?
I have conducted measurements on bubble sizes on 20 positions in the same foam, each of the 20 positions following a gamma distribution. From the boxplot the mean values appear very similar... Now I ...
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2
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0
answers
26
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Equality of p-value for cor t-test and anova F-test in simple linear regression
p-value for y, cor.test and F-test is the same 0.24 for below code. I assume this is due to F = t^2, but not entirely sure why.
...
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1
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39
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Comparing means with unequal n
I am trying to compare two groups to see if they are statistically different in how much time in seconds ($y$) they use one of two particular products $x_1$ or $x_2$. One person can only use either $...
