Statistical significance refers to the probability that, if, in the population from which this sample were drawn the true effect were 0 (or some hypothesized value) a test statistic as extreme or more extreme than the one gotten in the sample could have occurred.

learn more… | top users | synonyms (2)

0
votes
1answer
9 views

Significance of a cluster with respect to the whole dataset

I mainly am a machine learning guy and my knowledge of statistics is a bit limited. I have a (small) dataset of objects described by two categorical variables: $$ \begin{array}{|l|l|l|l|l|} \hline ...
0
votes
0answers
17 views

What statistics should I use for my comparison?

I am currently analyzing leaf senescence over two sites, using 6 species, each with 5 replicates. The senescence is measured in percentages and is linear. How could I analyse the two to see if there ...
0
votes
0answers
3 views

Which statistical test for statistical significance of positive result in 5 categories of samples

I have 5 categories rock samples and I am trying to understand how their fossil preservation differs and whether the difference is statistically significant. I determined the presence or absence of ...
0
votes
0answers
7 views

Determine statistical significance of web server response times

I am trying to analyze the performance of a web server. I've pulled from the logs a sampling over seven days of the hits for each individual page. From a histogram of the response times, I see that is ...
0
votes
0answers
10 views

Statistical test to check if mean of two groups are “significantly” same [duplicate]

Is there a statistical test, to check mean of two group is "sigificantly" same. Something opposite to Wilcoxon test. I was thinking may be running Wilcox test and if it not significant, then check the ...
1
vote
1answer
29 views

Closed form solution for t-stats and p-values in multiple regression

I am trying to build a spreadsheet that will perform multiple linear regressions on a number of data series using the closed-form solution. It was fairly straightforward to write the solution for the ...
0
votes
0answers
14 views

Why do we take the absolute value of weight of evidence when computing the information value?

I was looking at the explanation for Information Value calculation in STATISTICA and I find it a bit confusing: ...
0
votes
0answers
6 views

Significance test likelihood to detect a mean difference, and sufficient power [on hold]

Here is my question: I need help on part D. This is my answer but I think it's wrong. Any suggestions are very appreciated.
-2
votes
0answers
12 views

Significance Levels [on hold]

1.​A statistics professor has noted over many years that 13% of enrolled students withdraw from the introductory statistics class before the end of the semester. A salesperson suggests he try a ...
0
votes
0answers
3 views

Analytic determination of exact confidence intervals (without making approximations)

I would like to determine 95% confidence intervals for the mean of a negative binomial distribution. I have read a number of papers that use Gamma, Normal and Chi-squared approximations in order to ...
2
votes
2answers
94 views

Estimate statistical significance of a feature in a time series

I have a set of time series with events marked in the middle. Following the event there is a temporary dip in the series values followed by a peak so that the area under the curve is 0. ...
0
votes
0answers
22 views

which test should I apply to find which model is significantly different? [on hold]

I have two questions 1- regression I have performed many regression models (10 models) and therefore, I have 10 prediction columns and one column or more for my real data (independent variables) ...
2
votes
1answer
35 views

Clarification on statistical significance

“The variation achieved a 20% increase in conversions with 90% significance.” Unfortunately, this isn’t equivalent to, “there is a 90% chance of a 20% increase.” So what does it actually mean? ...
0
votes
0answers
13 views

Automatically grouping numbers [closed]

I have a few thousand instances of numbers, as in the example below. This is the only column of data that I have. I want to figure out what is the more optimal groupings for these numbers based on ...
8
votes
4answers
290 views

Develop a statistical test to distinguish two products

I have a data set from a customer survey, I want to deploy a statistical test to see whether there is significance difference between product 1 and product 2. Here is a data set of customers' ...
0
votes
0answers
23 views

Vector Statistical Significance [closed]

PS: If possible in R or math I am looking for the best way to do significance testing, but given multiple variables. Looking at my example below, there are 2 groups, and 4 variables. Each row is a ...
3
votes
0answers
74 views

sparse covariance/correlation thresholding

In our project, we would like to do some optimization on sparse matrices. The idea is to scrape massive amounts of data, form a covariance/correlation matrix, and form a sparsity pattern basically by ...
0
votes
1answer
45 views

How to determine if a weighted average is accurate?

I have the following problem. Consider that there is an election where n persons are voting. The goal of the election is to estimate the weight of a bag. Each person can vote for an integer value : ...
1
vote
0answers
14 views

Meta analysis; significance test of correlations

I have performed a meta analysis using the 'Metafor' package in R. I have some corrected correlations. Now I am wondering how I can calculate whether they are significant and whether there is a ...
21
votes
8answers
1k views

The abundance of P values in absence of a hypothesis

I'm into epidemiology. I'm not a statician but I try to perform the analyses myself, although I often encounter difficulties. I did my first analysis some 2 years ago. P values were included ...
0
votes
0answers
14 views

Comparing the expected and observed values of each item in a dataset separately

I have a set of points and for each point I have both observed and expected values. How can I compare the difference between the observed and expected values are significant for each data point. Note ...
3
votes
1answer
42 views

What happens in linear regression if Y's are not independently sampled?

What happens in linear regression $Y\sim X$ when the $Y$'s are not independently sampled and, particularly, may be autocorrelated? I believe the estimator will still work. But what will happen to ...
0
votes
1answer
40 views

Weibull distribution

I need to find a distribution that fail regularity condition.Maybe weibull distribution can be but I did not find why, please help me.
0
votes
1answer
28 views

How to judge which test is more difficult?

I used computer to automatically select 30 questions from a database, and forward to 20 students. Then I reviewed their answers, and used 1 to represent a correct ...
0
votes
0answers
42 views

Why does adding independent variables make all independent variables insignificant? [duplicate]

I am running a logistic regression in Stata to try to determine which independent variables potentially cause a response in a binary dependent variable. When I run certain independent variables ...
0
votes
1answer
26 views

How to determine if a value is significantly larger than other values?

My problem is the following: Let say that there is n persons voting for some values "a", "b", "c", ... For example, consider that 10 persons have voted for values "a", "b", "c", "d" and that the ...
0
votes
0answers
16 views

compute the ratio of odds ratios and its confidence interval

How would one compute the ratio of odds ratios and its confidence interval? for example: OR1=1.07; ci=0.88-1.29 OR2=1.27; ci=0.78-1.39
0
votes
0answers
42 views

Can p-value = <0.05 with CI that includes 0 using chi2 in Stata?

I am doing a pretty straightforward analysis in Stata comparing proportions of respondents in 2 groups (in this case, rural vs. urban) who agree with different questions on a survey. For one of the ...
1
vote
1answer
30 views

Strange two sample z test result in experiment

I performed an experiment on a virtual population wanting to see whether Vitamin C can positively affect performance on an IQ test. I gathered 80 people and grouped them into two groups of 40. ...
0
votes
0answers
24 views

Which is right? Individual variable t test or multivariate Hotelling t test?

So, lets say a hypothetical example. You have data of women aged 25-50 on their nutrition activity and measured for 737 such women(n,sample size) on 5 variables(Calcium, Protein, Vitamin A, Vitamin ...
0
votes
0answers
20 views

Kruskal-Wallis post hoc comparisons different results in different software used

I'm having some trouble analyzing my data because when I use StatSoft Statistica and run a Kruskal-Wallis, I get one set of values for multiple comparisons, but when the same analysis is run in XLSTAT ...
3
votes
1answer
42 views

Predict the weekday of a recurring event and its probability

Suppose, we have 100 observations of variable X. X is the day of the week (Sunday – Saturday) when a specific event occurs on regular basis. E.g. when a postman delivers a package every week for 100 ...
0
votes
0answers
11 views

Multiple Regression slope significance

Scenario : I create a model with 2 independent variables and one of them tests out insignificant. Questions: 1. What does it mean to have a statistically insignificant slope attached to an independent ...
-1
votes
0answers
16 views

Whether the following problem represents a Bernoulli trial (binomial)

I have the following problem but I am having problem finding the correct answer: A manufacturer recalls a doll because about 5% have buttons that are not properly attached. Customers return 43 of ...
1
vote
0answers
35 views

T test on whole sample or on averages

Background: Consider the following experiment: There are two groups of subjects, Group A have been treated with a drug that affects the muscle fibre diameter and Group B with a placebo. After ...
0
votes
0answers
17 views

Matlab survival curve log rank test

I am trying to do survival analysis in matlab and want to calculate log rank test scores among several curves. I found a possible code to do log rank here. But based on its description, it can only do ...
0
votes
0answers
25 views

Comparing difference between two polynomial regression models in R [duplicate]

I've been having some trouble in attempting to compare sets of data. I can't seem to analyse whether two models describe the same set of data, or if they describe different sets. Here is my a portion ...
3
votes
0answers
13 views

Multiple comparisons of parameters from non-linear regression

Hei, I want to compare parameters a_i and b_i estimated by nonlinear regression (y=a_i*x/(b_i+x)) for different data-sets (let's say 8 different data sets). I have calculated the non-linear ...
0
votes
0answers
23 views

Is there a way to test for significance with these data?

I am having trouble figuring out a proper statistical test for this data, if there is one. I treated leaves of a plant with a peptide and 24h later treated them with a pathogen. I scored both local ...
3
votes
2answers
32 views

Testing if distribution is similar between two groups

I have a variable young that is equal to 1 if a participant is less than 25 years old. I then have a list of of each ...
1
vote
1answer
25 views

Interaction term becomes more significant

Model(1): Y = A + B + $W_1$ + A*B Model(2): Y = A + B + $W_{1,2,3,4,5}$ + A*B A ranges from 0 to 70 while B ranges from 0 to 25; W refer to set of controls. In model (1) A (p<0.01) and B ...
0
votes
0answers
32 views

Which statistical test to use to establish different behaviour between groups?

I have got a dataset with a dichotomous groupid variable and many other independent categorical variables. My aim is to find out if subjects in first group behave differently than subjects in second ...
0
votes
0answers
19 views

For A/B test, how to show the result is significant?

I have a question: Assuming I have medicine A (new),and medicine B (old). I used two medicine on two groups of patients. After the test, I got two groups of variables, such as cell damage rate (for A ...
2
votes
1answer
84 views

How do you tell if you should use a one-tailed test or a two-tailed test in a t-test?

For example, how would you decide between which tailed test to do in the following experiment: Ethanol dilutions were made with different proportions and Daphnias were submerged in them to collect ...
1
vote
0answers
18 views

Statistical test for comparing two response options in the same survey item

Is there a way to determine whether the proportion of respondents that endorse one response option of a question is different than the proportion of respondents that endorse another response option of ...
1
vote
0answers
19 views

How do you assess data validity when sample size varies over time

Imagine that you have a customer feedback system where after a process people can press one of 4 buttons: (very happy, happy, sad, very sad) and an aggregation system reports how many people per hour ...
0
votes
0answers
45 views

lm and nls F test in R

I am trying to compare a linear model and other non linear models(Asymptotic, Logistic and Ricker) by means of an F test or a likelihood ratio test. I have tried anova(Linear, Logistic,Ricker, ...
0
votes
0answers
15 views

Which statistical significance test to use for nominal data collected from a within-subjects experiment?

I've collected some data from an experiment where I was evaluating a system. My independent variable had 4 conditions (call them C1, C2, C3 and C4). During the experiment, I asked six people to ...
0
votes
0answers
6 views

how to understand if 2 very correlated predictor influence the output?

I have a binary output $y$ and a small set of predictors $x_1, x_2,...$ Two of these predictors are very correlated. It is known that one of them has influence on the output we want to know if also ...
4
votes
0answers
51 views

What's the distinction between a “Null hypothesis statistical test” and any other test?

A recent hot topic of discussion concerns a journal banning the use of "null hypothesis statistical testing procedures (NHSTPs)" from articles submitted to the journal. I see this term used by some ...