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.

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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 ...
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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 ...
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2answers
84 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. ...
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21 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) ...
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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? ...
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13 views

Automatically grouping numbers [on hold]

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 ...
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3answers
268 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' ...
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23 views

Vector Statistical Significance [on hold]

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
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73 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 ...
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1answer
44 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 : ...
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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 ...
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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 ...
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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 ...
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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 ...
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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.
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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 ...
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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 ...
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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 ...
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15 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
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41 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 ...
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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. ...
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23 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 ...
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0answers
19 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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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
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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 ...
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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 ...
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2answers
31 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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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17 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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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1answer
11 views

Statistical signficance of aggregated terms

I work in retail analyzing the results of various marketing campaigns. Many of them are some form of direct messaging (Email, text message, Snail Mail, etc.). When we comb through the database and ...
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1answer
22 views

Determining sample size n for a plant experiment

I am testing plant health by looking at height, stem width, color, and content (antioxidants and the like). However, I was unsure how to determine a sample size for each measurement, in order to have ...
0
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0answers
9 views

What is the appropriate way to compare regressions between two time series

I have two temperature time series, both sampled at the same rate and over the same time period. What would be the correct method to compare the slopes of the linear regressions of these two datasets ...
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1answer
64 views

How can I measure difference between non-parametric data with many zeros?

I'm comparing two groups of students by their course activity and I'm struggling a little to determine the best way to test for significant difference. The data is non-normal, and very prevalent with ...
0
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0answers
11 views

Missing Data: Profile or Pattern?

In missing data analysis: is the term "missing profile" the same as "missing pattern". I think they are the same; but when I Google for "missing profile" together with missing data I don't get too ...
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0answers
11 views

Significance of a correlation considering missing data

So I'm dealing with two timeseries, of which one contains quite some missing data (between 10-60%). I'm excluding some datasets which contain exceptional much missing data, but still I would like to ...
3
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1answer
77 views

Measures to compute the similarity between two time series whose amplitude is periodic ignoring any phase differences

Question: Given two time series whose amplitudes are periodic, what measures could i use to quantify the similarity between them ignoring any phase difference? Specifically, i am looking for measures ...
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1answer
53 views

Quantitative importance for interacting variables in Artificial Neural Networks?

Is there any common/sound method to quantify (similar to T-test or F-test in regression models) the measures of influence and significance of terms in Artificial Neural Networks? By terms I mean both ...