Tagged Questions
1
vote
0answers
27 views
How do I analyse a two-alternative forced choice test?
I have recently as part of my bachelor project at my university conducted a two-alternative forced choice test. I have looked at ways to say something with significance about which images (the test ...
4
votes
0answers
36 views
How to test whether mean and variance is the same in two small samples?
I would like to test two relatively small samples against the null hypothesis that both their means and variances are the same. The alternative would be that they in fact differ. I saw a post on this ...
1
vote
0answers
23 views
How to extend multiple regression hypothesis tests to multivariate?
I have a basic multivariate regression model $\mathbf{Y}$ = $\mathbf{XB}$ + error
$\begin{bmatrix}y_{1i} \\ y_{2i} \\ \vdots \\ y_{ki} \end{bmatrix}$ =
$\begin{bmatrix} X_{11} & ... & X_{1p} ...
0
votes
0answers
24 views
Statistical Significance test for difference in FScore
For a classification task, I have developed two methods and FScore(harmonic mean of precision and recall) of both the classes serves as the performance criteria. How can I check whether the difference ...
1
vote
0answers
15 views
Significance testing for a group of samples
For instance, I have a bar chart - in which I have 4 samples/bars. for these 4 bars, I want to check statistical significance for all combinations.
How can I do it? Can unpaired t-test be used - to ...
2
votes
0answers
15 views
How to test significance of pre-post difference scores on 8 measures (1 group)
I have a set of pre and post treatment scores on 8 measures. I'd like to test which of these show significant improvement after treatment. If I use within-subjects t tests it will mean carrying out 8 ...
2
votes
1answer
69 views
How to compare two datasets using metrics drawn from unknown distributions and with small sample sizes?
I have two datasets consisting of metrics from several experiments. Dataset 1 is the collection of results of experiments E performed by user A on product A, repeated N times. Dataset 2 is the ...
3
votes
0answers
156 views
Ratios of means - statistical comparison test using Fieller's theorem?
I would really appreciate any suggestions with the following data analysis issue. Please read till the end as the problem at first may appear trivial, but after much researching, I assure you it is ...
1
vote
0answers
21 views
Test regression parameter against a constant in SPSS
This is a pretty basic question, but I can't find an answer by searching for different statements of the same problem.
Is there a straightforward way to test if a regression parameter is different ...
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
1answer
43 views
Conservative confidence interval
One month before the election, a poll of a large number of randomly selected voters showed 65% planning to vote for a certain candidate. The newspaper article reported a 90% conservative margin of ...
0
votes
1answer
19 views
Statistics test for concentration of extract effecting germination
I am undertaking biology course work and am a little stuck.
My experimental hypothesis is: There is a significant correlation between increasing tomato extract concentrations and reduced seed ...
0
votes
0answers
36 views
How do I prove that my results are significantly better in this situation?
I have a test suit for an optimization problem with 270 problem instances. For all these instances I have a lower bound and a single solution of another algorithm. I do not own this algorithm and am ...
0
votes
2answers
27 views
Hypothesis / Statsitical significance between continous variable and dependent binary variable
Sorry I am a stats newbie, I understood that I can use the search feature, I tried to search but I am afraid that I am not using the right terms and the results returned are not quite relevant to my ...
1
vote
0answers
47 views
Comparing sets of non-normal distributions
Apologies in advance if this question seems trivial -- I am a biologist and have little experience in statistics.
I have six non-normal distributions (they're positively skewed): three are replicates ...
24
votes
5answers
944 views
Regarding p-values, why 1% and 5%? Why not 6% or 10%?
Regarding p-values, I am wondering why 1% and 5% seem to be the gold standard for "statistical significance". Why not other values, like 6% or 10%?
Is there a fundamental mathematical reason for ...
-2
votes
3answers
71 views
Determining if awards are fair
Imagine a population of people where $x\%$ have blue hats and $(100-x)\%$ have green hats where every year some people are awarded prizes. The rule is that everyone should have an equal chance of ...
3
votes
0answers
63 views
binomial test for testing significance of classification very sensitive to hits count
I'm doing a multi-class classification task and I wonder if I'm doing the binomial test correctly since it is very sensitive to the count of correctly classified trials (hits count).
Say, there are ...
0
votes
4answers
62 views
t-test equivalent for samples, given a distribution of unknown form?
If there are two samples from a distribution whose form is not known, and which is certainly not normal, how can one ascertain the probability that, by random chance, their means/medians are ...
0
votes
1answer
55 views
Need help selecting appropriate statistical tests
I have several data related questions I am hoping to get answers to. I have a 4-week intervention (no control group) and all participants are given and pre and post test assessment consisting of two ...
0
votes
0answers
76 views
How to set the significance level in a hypothesis test correctly
I have difficulties understanding probabilities.
Let's imagine I have a test based on time series regressions and my null hypothesis is that I will pass my next exam in statistics. The test is ...
0
votes
0answers
247 views
Stata: wald test ratio coefficients from separate models
Dear Cross Validated people,
On Stata, I am using a probit model on data from a correspondece test on the labour market. The unit of observations are people, and Y=1 indicates that the individual ...
0
votes
0answers
28 views
Can significant relationship be used with significant difference at same time?
Usually I read about either testing for significant relationship or significant difference but can they used both to prove something? For example, assume a shop wants to compare its profits per month ...
3
votes
0answers
53 views
Testing for mutual exclusivity
So first, sorry if I use non-standard vocabulary, since I am not an expert. Please feel free to correct.
I would like to know if a set of genes in a patient cohort are mutated by a mutually exclusive ...
-1
votes
1answer
50 views
How to test a large sample if it is normaly distributed?
I am dealing with normaly testing of large samples. As stated here:
Is normality testing 'essentially useless'?
Normally testing is essentially useless, if the sample is too large. Even ...
0
votes
0answers
24 views
How to prove that the east teams are higher in the ranking that west or vise vera?
If we want to compare the rankings of teams that are from east or west, how can we show that east or west have higher rankings than other?
Example
...
0
votes
0answers
82 views
How to rank the elements for use in Spearman rank correlation?
If I have 50 items and I want to compare the top 30. I have several cases to do the ranking , so which one is correct?
For simplicity I will replace in the example below 50 items with 5 ( A,B,C,D,E) ...
0
votes
0answers
41 views
which test to use if you only have summary statistics? (non-normal)
Here's the basic problem: visiters to our website were randomly put into one of 7 different groups, and we want to compare the activity of users in the different groups on a downstream site. The ...
0
votes
1answer
48 views
How to prove that test 1 produces more results than test 2?
If I have 2 tests applied on a set of data, both tests either produce a result ( assume = 1) or no result ( NA , assume = 0 ). Is there a way to prove that test 1 produce more results than test 2 with ...
0
votes
2answers
98 views
Samples that will result in a large p-value
Consider a one-sample t-test regarding the population mean time to
complete a task with a one-sided alternative hypothesis of Ha: μ < 10
minutes. A random sample of times to complete the ...
2
votes
2answers
146 views
Interpreting p-values
I am a little confused about what p-values mean under Fisher's signficance testing & Neyman-Pearsons hypothesis testing.
Fisher uses p-values as a continuous measure of evidence against a null ...
1
vote
1answer
102 views
Population mean and hypothesis testing
The national average price of a gallon of regular gasoline is 3.71
dollars. Linda would like to assess if the average gas price in her
city is significantly higher than the national average. ...
2
votes
1answer
33 views
Learning about a population mean
Assuming $H_0$ is true, what is the distribution of the test statistic?
t(29)
Assuming $H_0$ is true, what is the expected value of the test statistic? 87.70
The sample mean of 87.7 was _ standard ...
0
votes
0answers
78 views
What test of independence of sample proportions is appropriate when n is very large and p is very small?
I have the (not necessarily veridical) impression that typical textbook independence tests of proportions are intended for use the proportions involved are not super small.
In my case n may be 10^8 ...
0
votes
1answer
67 views
Statistical significance of ordered binary vectors
I have a program to predict some values for people. For validation, I keep track of whether the prediction is correct or not, which gives me a binary vector with a length of about 600.
To test if it ...
1
vote
1answer
122 views
Standard Error used in Hypothesis Testing and Confidence Interval construction
In the excellent Practical Statistics for Medical Research Douglas Altman writes in page 235:
"Because the standard error used for calculating the confidence interval differs from that used in ...
-1
votes
1answer
184 views
Simple multiple choice for test statistic and significance level
A study aims to determine if a new tutoring program (method 1) is better than standard preparatory program (method 2) to prepare students for the SAT. It measures the proportion of students who score ...
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 ...
1
vote
2answers
50 views
I want to compare two groups of coin tosses with different number of tosses
I have a list of results of two different groups of coin tosses generated by http://www.wolframalpha.com/input/?i=10+coin+tosses. But the number of tosses is different: There are 10 in one group and ...
3
votes
1answer
108 views
Finding the test statistic for a majority hypothesis
In a survey of 1070 Ann Arbor residents, 59% supported a ban on bicycles on downtown sidewalks in certain areas with high pedestrian traffic. A city administrator wants to determine if a majority of ...
1
vote
0answers
66 views
Statistical Test for Differences in Groups Based on Multivariate Function/Map
I've recently run into an issue where I am trying to test for a statistical difference between two groups, where each element of a group is itself a data object. For any pair of objects, I can ...
1
vote
0answers
55 views
significance test to use for multiple conversions in an A/B test
What is the proper way to measure significance in an A/B test, when a visitor can potentially "convert" more than once?
I understand a chi-square test or z-test are most often used for A/B testing, ...
0
votes
1answer
78 views
3
votes
2answers
92 views
What does statistical power mean when we are interested in the probability of correctly not rejecting the null hypothesis?
It seems that statisticians are usually only interested in statistical power. In other words, they are interested in the probability of correctly rejecting the null hypothesis.
What if we are ...
1
vote
1answer
117 views
Differences between groups
I am currently doing a research on effects of writing styles on the perception of reader.
Currently I have the following 4 groups
...
2
votes
3answers
147 views
Two fair coins, why increasing trials in prop.test not reduce false positive?
I am simulating two fair coins and running a prop.test, how come increasing number of trials doesn't decrease false positive? I'm suspecting it's in some underlying ...
2
votes
0answers
83 views
How to test if two coins have different biases?
probably a noob question because I'm a noob.
I have two coins, A and B. For each coin I have a sample of the results I get by tossing it. My null hypothesis is that A has equal or higher probability ...
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
3answers
196 views
Direction of relationship in 2x2 contingency tables
I've been studying contingency table analysis and got to experiment a little bit with Fisher's exact test and Fisher's power test. Now I want to be able to determine the direction of the ...
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 ...
