Questions tagged [statistical-significance]
Statistical significance is a characteristic of a statistic viewed in light of a null hypothesis and a given significance level. It reflects whether the statistic belongs to the rejection region (is statistically significant) or the acceptance region (is not statistically significant).
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$\chi^2$ test of homogeneity for three-way contingency table
I have a three-way contingency table in which the marginal totals for two sides are fixed and for the third are random. I'm wondering how to perform a chi-square test for homogeneity for such a three-...
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How to know whether the six spatial features values (in 3-time period) significantly differ from each other? [closed]
I am currently bothered on how to statistically analyze my simple data as shown below.
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How can I obtain null and residual deviance/degrees of freedom for assessing model significance?
I am trying to determine model significance using:
1-pchisq(null deviance-residual deviance, null df- residual df)
I have 5 models:
Four models were estimated ...
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Interpreting p-values associated with correlation measurements
The "Introductory Statistics with R" book contains a section that deals with correlations (section 6.4 in the second edition). The book shows Pearson, Spearman and Kendall correlation coefficients ...
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What is the best way to determine if pageviews are trending upward or downward?
Given the following dataset for a single article on my site:
Article 1
2/1/2010 100
2/2/2010 80
2/3/2010 60
Article 2
2/1/2010 20000
2/2/2010 25000
2/3/2010 23000
...
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How can I get a velocity of how much this link is trending?
The above image represents an article's page views over time. X axis is days with 9 being the most recent day. The y-axis is number of pageviews. I'm looking for a decent, not to complex either ...
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Is there a way to determine the significance of a change in a d' score?
I have a series of scores in a signal detection task. For each block of scores (i.e. a set of scores from one participant on one day) I have calculated a d' score which I am using as an indicator of ...
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How to compare two groups of patients with a continuous outcome?
I am performing a retrospective study on patients looking at the size of their nostril (continuous variable measured in millimetres) and the need for treatment which is either conservative or surgical ...
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What statistical test can I use to detect clumping?
I have time series data that represent dates/times of trades taken in a financial market.
I would like to assign a score to this data that represents whether the trades are ...
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Testing significant effect in 2 by 2 factor design on a binary outcome
I have 4 groups each consisting of 1000 recent college graduates, and I am studying employment immediately after graduation. 2 groups took a business class in college, and 2 groups took a math course ...
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Difference in means in multiple-choice poll
Let's say that N randomly chosen persons where asked a question where the answer could be in either of X categories. For example, 500 persons where asked which of the top 5 political parties they ...
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What is the meaning of rank in the context of change-detection?
In a technique that uses CUSUM for change-point detection in this paper, the first step is given below:
Let $x_1, x_2,..., x_n$ be the $n$
samples in an event-series. The
samples are ranked in ...
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How to compare the effectiveness of medical diagnostic techniques?
A pathologist friend came to me for help with the following question for a research project. The goal is to compare the effectiveness of three different diagnostic techniques. The data set is as ...
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How to test whether correlation measures differ when controlling or not for a third variable?
If the correlation between demographic dissimilarity and satisfaction is $r=.-14$ and the partial correlation, with career development partialled out, between demographic dissimilarity and ...
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Can I split a series of observations of a variable over time into two groups instead of working with time series?
First of all, I’m new to statistics and this is the first time I am trying to apply it to a real world problem.
I am doing analysis of a series of observations of a variable over all weeks of a year. ...
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How to assess differential risk of disease across three groups after adjusting for other risk factors?
I have 3 different groups: A, B, and C:
A (has a medical condition) has 30 entries
B (another medical condition) has 31 entries
C (control group) has 55 entries
All participants have information ...
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Does significance test make sense to compare randomised groups at baseline?
Many randomised controlled trial (RCT) papers report significance tests on baseline parameters just after/before randomisation to show that the groups are indeed similar. This is often part of a "...
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Determining if change in a time series is statistically significant
I have the total number of calls received each week and have plotted them on a chart, going back nearly 3 years.
By eye it seems that there was a massive drop over Christmas, that doesn't seem to ...
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Statistical significance of changes over time on a 5-point Likert item
Context:
I have two data sets from the same questionnaire run over two years. Each question is measured using a 5-Likert scale.
Q1: Coding scheme
At the moment, I have coded my responses on a [0, 1]...
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Interpreting significance of predictor vs significance of predictor coeffs in multinomial logistic regression
I have a multinomial logistic regression with dependent variable valued in {-1,0,1} (reference category is 0) and a number of continuous and discrete predictors. After running the regression a ...
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What is a good statistical test for independent replicates?
I have a series of measurements in which something is sampled and placed into either category 1 or category 2. I have 3x2x3 factors for each set of measurements, and each set of measurements is done ...
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How to assess effect of intervention in one state versus another using annual case fatality rate?
I am a beginner in statistics with just basic knowledge. I have these data: cases, deaths and CFR (Case Fatality Rate-deaths per 100 cases) of a disease for 17 years (1994-2010) from 2 neighbouring ...
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How to do Chow test for constancy of parameters across 2 groups
I am a beginner in statistics and poor in mathematics. I am trying to to assess effect of intervention in one state versus another using annual data.
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Choosing sample size to achieve pre-specified margin-of-error
If I want to achieve a margin-of-error of <= 5 % for a representative population sample, how large a sample do I need when: The interviewees are picked from X regions and from Y age groups? That is,...
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How to determine statistical validity of results
I have two exclusive groups of people and a counter of how many events happened for each group.
Lets say group 1 has 7000 people and group 2 has 3000 people.
group 1 had 50 events and group 2 had 40 ...
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Poisson distribution and statistical significance
Lets say I have a website which gets 100 hits per day (mu = 100). Yesterday my website got 130 hits (x = 130). If I assume a Poisson distribution, then the probability of getting 130 hits is:
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What is the right statistical test to use when attesting claims like "60% people switched over from group A to group B"?
My problem is this:
There are 52 people divided into 5 groups: A, B, C, D, and E. From stage 1 to stage 2, they either stay in the same groups, or change groups. The following table shows how many ...
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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 ...
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Investigate ratios between two groups
I've got some data that has this basic shape (using R):
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How to fix the threshold for statistical validity of p-values produced by ANOVAs?
I have run experiments on a group of users under two conditions, measuring the time it took users to finish their experiments. I used a cross-over design where half of the users started in the first ...
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Assessing significance of correlation
I have two variables, and I can calculate e.g. the Pearson correlation between them, but I would like to know something analogous to what a t-test would give me (i.e. some notion of how significant ...
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Analysing questionnaire data
I want to test if there is a rivalry among two siblings in a family. I have 15 questions in my study and I let my 100 respondents ( distributed equally to two siblings) ranked them 1 to 15.
How ...
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Analyzing the difference between two datasets where one is a subset of the other
I apologize in advance for the vague title, but I couldn't think of anything better.
I have two datasets, where one is a very small subset of the other. The percentage of people who have a specific ...
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What is a good measure (or set of measures) for the difference between two sample sets?
I'm doing some software testing where we are measuring specific latencies. Generally we run the same test several times to just eyeball the results and make sure that they are consistent across runs. ...
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How to tell if the slope of a line is 0 or there is just no relationship?
I am attempting to examine the change in slope between a predictor and response over two years. In year 1, it is definitely positive. (Linear regression, the 95% CI of the slope doesn't overlap 0). ...
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When is a deviation statistically significant?
In a double-blind study, when are deviations from the control group considered statistically significant? And is this related to the number of samples?
I realise that every experiment is different ...
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Statistical significance with sample size of 5 or less
Should small sample sizes of 5 and less be included in reports?
This is an area of medical training that is currently being reported only to the course level trainers and statistically not included ...
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Removing macro-level time variance
The title might be a bit misleading. Unfortunately statistics is not my area of forte, so gentle guidance along the right path is much appreciated. That said, here's my problem:
I'm working on ...
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What method to use to test Statistical Significance of ASR results
I have 2 ASR (Automatic Speech Recognition) models, providing me with text transcriptions for my testdata. The error measure I use is Word Error Rate.
What methods do I have to test for statistical ...
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Calculating significance of difference between two binary values on one dataset
Suppose my sample comprises 350 instances. Each instance has two independent binary (pos and neg) evaluations, A and B. If my ...
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Comparison of two values in a statistically sound manner
For a university paper, I have to compare whether two program versions are statistically significantly different. The comparison in terms of runtime performance is straightforward -- I determine ...
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Do the null hypotheses used for benjamini-hochberg have to be identical?
There are some cases where I would like to correct for multiple comparisons where the null hypotheses vary.
For example, if I am performing a chi-squared test or a fisher's exact test on multiple ...
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How to test if change is significant across multiple categories?
Here is a look at my data. We asked the same respondents (n=~400) to provide us with their current and future consumption as a proportion of total expenditure. Plotted here are the mean proportions of ...
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What is the best statistical test for a time series? [closed]
I have a simple time series with 5-10 data points per data set at regular intervals. I am wondering what is the best way to determine whether two data sets are different. Should i try t-tests on ...
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Using the distance of p-value from alpha
I have two statistical tests which are inverse of each other, meaning that the null hypothesis are reversed. I want to use both the tests to take a decision. For this purpose, I am planning to do the ...
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Measuring statistical significance of machine learning algorithms comparison
Let us consider a comparison of two machine learning algorithms (A and B) on some dataset. Results (root mean squared error) of both algorithms depend on randomly generated initial approximation (...
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How to look for valleys in a graph?
I'm examining some genomic coverage data which is basically a long list (a few million values) of integers, each saying how well (or "deep") this position in the genome is covered.
I would like to ...
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How to choose df for comparisons between summary statistics (e.g. slope values)?
In order to correlate or compare means of two dependent variables.
In my case, I need to correlate individual (e.g. subjects=30) slope values from different conditions (e.g. conditions=4), and each ...
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How to deal with correlations not statistically significantly different from zero?
I often find parts of financial correlation matrices not statistically significantly different from zero. Sometimes, these correlations have a tangible effect on results - low correlations lead to ...
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Assessing the significance of differences in distributions
I have two groups of data. Each with a different distribution of multiple variables. I'm trying to determine if these two groups' distributions are different in a statistically significant way. I ...
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