Tagged Questions

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
11 views

Proportion Comparison

I have data from baseline and end line surveys. Baseline was conducted before intervention in children and end-line was conducted after intervention in the same population. Study population is same ...
0
votes
0answers
14 views

Statistical analysis of variable data

I have the statistical research data. I have 6 treatments with 3 boxes for each treatment. I am raining on the treatments every week and collecting data. The data is variable within boxes and also ...
0
votes
0answers
19 views

difference between machine learning and stastitical technique [duplicate]

Is there any difference between machine learning and stastitical techniques. I have searched a lot some researchers say that there are some overlap some are saying there is no difference.Can you give ...
0
votes
0answers
4 views

LOO or LMO (Q2) [on hold]

In the Leave Many Out (LMO) or Leave One Out (LOO) validation techniques. Does it make sense to achieve a Q2 >0 or >1? If it is possible, I would like to know what does it mean? If it is not ...
1
vote
2answers
46 views

Comparison of machine learning algorithms

Suppose i have taken 8 machine learning algorithm which is used researchers more frequently.I have applied these 8 machine learning algorithm over 8 datasets which is publickly available on internet. ...
0
votes
1answer
13 views

How to compare four sets of experimental data and decide if the differences are significant?

For a school science fair project, my daughter randomly divided a population of subjects into a control group and three experimental groups. We recorded the time each subject took to perform a certain ...
1
vote
0answers
8 views

Test for non-uniform sampling from a sequence without replacement?

I have a dataset that essentially amounts to a sample of K unique elements from an ordered sequence of length N. I believe that elements are more likely to be sampled from certain portions of the ...
3
votes
1answer
60 views

Interpreting results of chi-squared

Situation: A/B test of a single website change on a landing page. Alternating visitors to the landing page are shown a variation. The goal is to convert more visitors into customers. With data that ...
0
votes
0answers
13 views

Infer significance (in trends) in time-series data

I got a dataset with multiple time variables (i.e. 21 fixed measurement times). It is expected that a (downward) trend over time can be discerned in these variables. When plotting scatterplots I find ...
0
votes
0answers
12 views

Optimizing selection from varying sets

On pages of website(s) I have a set of potential messages to choose from and only one or two slots to show them in. (think 'this product is on sale' or 'this product is new'). On each page the set ...
0
votes
1answer
35 views

Statistical test of stock returns product

Say I have a sequence of stock returns: $X_1, ..., X_n$. Then I make a sample of products: $X_1X_2, X_2X_3, ..., X_iX_{i+1},..., X_{n-1}X_n$ How to test, if the sample mean is significantly different ...
0
votes
0answers
20 views

nonsignificant predictor becomes significant

This may be a question with an obvious answer. I am trying to predict change in a continuous variable over time using a linear mixed model in SPSS. There are 4 time points. Ultimately, I would like to ...
0
votes
0answers
10 views

Substantial changes in significance level when adding more variables to the model [duplicate]

I have a multiple regression model. When I add one more independent variable to the model the significance level of two of my original independent variables suddenly get insignificant. How come? All ...
0
votes
0answers
8 views

Finding Confidence for locations?

I have a question regarding finding confidence intervals for location. The question is as follows, I have a set of coordinates (X,Y) where X is the latitude and Y is the longitude. Suppose, if I ...
1
vote
1answer
14 views

Best statistical method to show different performance week over week

I am trying to get best statical method to show performance of accumulative revenue by customer compare week over week. Currently I have about over 100 customer charts compare by hour from same day ...
0
votes
0answers
14 views

Statistical Significance of Turnaround Time

My laboratory recently implemented MALDI-TOF MS for identification of gram negative rods in blood cultures. I collected data retrospectively from laboratory reports comparing the time from isolation ...
1
vote
2answers
28 views

paired-sample t-test

I have taken weight measurements before and after a treatment. When I run a paired sample t-test and if there is a significant change, would it be possible to make the claim "95% of the time ...
1
vote
0answers
5 views

Statistical comparison of 2 dependent cohen's ds

How would I statistically test the significane of the difference between two Cohen's d derived from different tests within the same sample? Specifically, in my neuroimaging data metabolism in brain ...
0
votes
0answers
35 views

Statistical Test for Two-Alternative Forced Choice Task (2AFC)

I conducted a learning experiment and assessed whether participants learned with a two-alternative forced choice (2AFC) task consisting of 100 items (25 items of category 1, 25 of category 2, items of ...
-1
votes
0answers
32 views

Statistical significance to a population

I have a question in regards to statistically significant sample sizes to a population. I am working with data in excel and wanting to put the formula for this into the workbook as well but have run ...
0
votes
0answers
10 views

Test(s) For Comparing qPCR results / ΔΔCт values

To be clear, I'm talking about real-time polmerase chain reaction (qPCR), not Principle Component Regression. Though from a company selling qPCR reagents, here is a good walk-through of the ...
0
votes
0answers
22 views

How to CORRECT un-reliable and un-stability in the prediction results

Currently, I meet such questions when building Random Forest model using my data set. My full data set: X_lab: 839 * 469 and y_lab: 839 * 1 which is for all labelled data and X_unl: 20346 * 469 which ...
0
votes
0answers
12 views

regarding the statistics to test the impact of some subset values on a given variable

For a given variable, there is a set of values. We know that these values can belong to different clusters. For instance, a lot of values center around a small value while other values center around a ...
0
votes
1answer
38 views

How to ReSample the Training DataSet

I have a training dataset which differs significantly on several parameters (t-test/f-test) with the test set (for which the labels are not known to me.). I am thinking of re-sampling from the ...
1
vote
0answers
11 views

Conditions on ratio of $\frac{\sigma_{BIB}^2}{\sigma_{RB}^2}$

I'm attempting to solve a question about the variances of random block design versus balanced incomplete block design. I feel I am close to having an answer, but I'm not quite there yet. Question: ...
1
vote
1answer
16 views

Exploring Diffrences and Agreement with Wilcoxon and Kendall - both tests show significant findings

I calculated a Wilcoxon Signed Rank Test to investigate differences between a pair of dependend variables. Also I conducted a Kendall's tau-b on the same variables. Surprisingly both tests get ...
0
votes
1answer
24 views

How to present statistical significance results among more than two datasets?

Let us say that we have 5 sets of data: $$ a = (a_1, a_2, \dots, a_{10}) \\ b = (b_1, b_2, \dots, b_{10}) \\ c = (c_1, c_2, \dots, c_{10}) \\ d = (d_1, d_2, \dots, d_{10}) \\ e = (e_1, e_2, \dots, ...
0
votes
0answers
15 views

Is it Complete or Partial mediation? Or no mediation at all?

Kindly explain the given situation, is it partial, complete, or no mediation at all?
1
vote
1answer
20 views

Finding Bias$(s^2)$ in incorrect linear model

I am unable to find the bias of the sample variance estimator in this problem. Unfortunately I keep coming up with Question: Suppose that the true linear model is $y = X_1\beta_1 + X_2\beta_2 + ...
0
votes
0answers
6 views

How can I calculate the statistical significance for two different proportions of the sample? [duplicate]

I provided two English sentences for the same group of students to judge as grammatical or ungrammatical. 70% of the students judged the first sentence as grammatical whereas only 37% of the same ...
0
votes
1answer
40 views

Standardized regression coefficients

I have a question regarding standardized regression coefficients and the correlation matrix. I have a two part problem that I am working on, and I need to show that the correlation matrix R is equal ...
0
votes
0answers
17 views

Statistical significance of differences between percentages

I have a problem annoying me. I have associative word lists which formed by 150 participant's answers to given word. At the same time, i gathered information about word's valance with a 5 point Likert ...
0
votes
1answer
41 views

statistical hypotheses

A company that packages peanuts states that at a maximum 6% of the peanut shells contain no nuts. At random, 300 peanuts were selected and 21 of them were empty.With a significance level of 1%, can ...
1
vote
1answer
28 views

A/B/C Testing - Aggregate data for comparison?

Let's say I have 3 ads: A, B and C. These ads perform as follows- ...
1
vote
0answers
29 views

Certainty estimate for prediction of largest of several converging variables

Problem I want to have an estimate for the certainty which of several (3-4) variables is the variable with the largest value, given some sample values which should eventually converge to different ...
1
vote
0answers
38 views

Jonckheere-Terpstra Trend Test Use and Effect Size

I would like to find out if there is a statistically significant increase among four groups. I have 4 ordinal groups (ex group 1 is count 1-20, group 2 is count 21-30 etc) and I have data for each of ...
2
votes
0answers
53 views

Show alias coefficient of Plackett Burman design equals $r_{ij}=\frac{c_{1i}'c_{2j}}{N}$

Consider a Plackett Burman design with N rows and let $\beta_{1}$ be the of the regression coefficients corresponding to the main effects and let $\beta_{2}$ be the vector of the regression coefficients ...
0
votes
0answers
10 views

M statistic and software ProtoArray Prospector

I would like to reproduce the statistical result in this paper: http://www.ncbi.nlm.nih.gov/pubmed/24947363 They said "the M-statistic test in ProtoArray Prospector was applied to the normalized ...
0
votes
0answers
31 views

Monte Carlo test for spatio-temporal randomness

I have a collection of discrete spatio-temporal observations $d(x,y,z,t)$ on the surface of a sphere. The data is sparse and is in the order of ~100 points, but there is a bimodal clustering of these ...
1
vote
1answer
43 views

Multiple Regression - Residual Analysis

I am doing a multiple regression analysis regressing GPA against several 0/1 indicator variables (representing course completions). My fitted vs. residual plot is biased and looks awful. See below. Is ...
4
votes
1answer
186 views

How to interpret variables that are excluded from or included in the lasso model?

I got from other posts that one cannot attribute 'importance' or 'significance' to predictor variables that enter a lasso model because calculating those variables' p-values or standard deviations is ...
1
vote
1answer
60 views

If $\frac{(2n-1)s^2}{\sigma^2} \overset{}{\sim} \chi^2_{2n-1}$, can I take the variance of both sides to get an equality relation?

I currently have a standard result regarding variances and it looks like: $\frac{(2n-1)s^2}{\sigma^2} \overset{}{\sim} \chi^2_{2n-1}$ that is, it is approximately a chi-squared distribution with ...
0
votes
2answers
70 views

Proper Statistical Test for Binary Data

I looking for the best statistical test to apply in a particular situation and I hope I can find here the answer(s) I'm looking for. First of all some details: I'm studying 33 different mutants of a ...
0
votes
0answers
14 views

Three stage cluster sampling

I was just curious if anyone knew where to find information on three-stage cluster sampling. There is a significant amount of information on two-stage cluster sampling, but I am unable to find ...
0
votes
0answers
24 views

How to calculate sample size for poll / ranking

Let's suppose there are Y options to choose from. I'd like to run an experiment with a sample of n participants (from a larger population), each will choose 1 option from the Y alternative according ...
0
votes
0answers
81 views

Estimating the uncertainty of a bias and a scatter

I have one single set of observational data. Assuming I know the right answer for one property of this data set and then I use one tool to measure this quantity. To get an estimate of the amount of ...
0
votes
0answers
44 views

What constitutes a significant drop in speed of vehicles on a 40mph road?

A friend had an incident near where he lives recently that is similar to my line of work (currently) that made me think what constitutes a significant drop in speed as a result of a change in road ...
1
vote
1answer
27 views

What kind of test is this?

I have a client that wants to test 3 pricing options to visitors of a website. All options are for the same product and service (no difference except pricing). Their current idea is to present all 3 ...
2
votes
1answer
43 views

Multiple Linear Regression: Obtaining a Stable Model

I am working with a data set of ~1200 rows and 60 variables, and I'm trying to build a multiple linear regression model. I do this by separating 10% of the dataset to be used for validation and I use ...
0
votes
2answers
26 views

Understanding COVARIANCE when using same scale

Assuming that an experiment has 3 variables. Time, Temperature inside, Temperature outside. Also, considering that both the temperatures are measured using the same scale say Degree Celsius. If the ...