i'm doing my master thesis and i'm searching for a way to analyse differences with small samples. The smallest is n=4 (1vs 3). Is there an option to analyse potential significant differences with this small samples? I don't think so but i'm pretty new in statistics, so i would be glad to hear your answers.

friendly regards]]>

I am currently working with two different datasets. In the first one, I have the mass of 30 individuals. In the second one, I have the force of 90 individuals. I took the residuals from a linear regression to get rid of the size effect. Still, I have 30 and 90 residuals, respectively.

What I would like to do, is testing if there is a correlation between the residuals of the mass, and the force. Using either a correlation test or a linear model. But, as it should be paired data, R...

Correlation/LM of residuals with different length]]>

We're handling various data in our statistics courses at the moment and I have gotten back to using R....

In any way, as the title reads I've ran into a bit of an understanding issue in the exam-preparation for the data description part of the exam.

From what I've gotten, the ECDF shows the distribution of relative frequency up to X.

Meaning if I have a dataset:

1 1 3 3 4 4 5 5 6 6 total:12

2/12 4/12 6/12 ...1...

Empirical distribution function]]>

I am obviously no stats major but am having trouble with the analysis in my research. I am basically looking at the mean BMI (Normal, Overweight, Obese) in three different groups of individuals (Heart attack patients, Neurological patients, and Other).

Which test should I do to

1) see the differences in mean BMI across the groups of individuals

2) See the differences between mean BMI within just the heart attack patients

Thank you!

edit: if anyone knows how to do this on SAS as...

Basic Stats - T-test, ANOVA, Chi sq?]]>

Thanks for taking the time to read this. I'm a final year PhD student. I recently ran an experiment where 9 pieces of information was displayed to participants in a driving simulator. Participants wore eye tracking and fixations to each of the pieces of info was measured.

During two of the trials, all participants experienced two conditions. I want to see if there is a significant difference in fixations to each of the pieces of information between these two conditions.

I could...

Test for 9 Dependant variables, 1 Independent variable, Same Subjects]]>

Is it possible to use Logistic Model?]]>

as part of a module I will present a statistics paper to my fellow students. Unfortunately, I have some difficulty in understanding and would like to ask you for help. The paper says:

To test our proposed hypotheses for the second goal of this study, hierarchical regressions were runwith sex, age, sexual orientation, being astudent or not (block 1), and the Big five personality domains (block 2) as independent variables and the 13 Tinder motives as dependent variables...

R squared and F change in R squared in an hierarchical regression]]>

Currently I'm doing a Master thesis and I have a question related to that. I'm running a regression and I created a matched pair design sample (based on firm size, industry and year). However, my regression already has these variables added as control variables. I have read papers (in top journals) who also run a matched pair design regression based on a certain variable (for instance return on assets), but also have added this variable as a control variable. To me this seems...

Matched pair design and control variables]]>

Thank you!]]>

Is it valid to keep generating & testing new hypotheses on the same dataset even though the data weren't specifically collected to test those hypotheses, or does this produce a multiple comparisons problem? I think think it's perfectly valid as long as...

when does multiple comparisons become a consideration?]]>

Please see the attached table.

I'd like to test if each proportion belongs to the same population.

Can you please indicate which statistical test is the appropriate to use? I would help me if your answer is in terms of a statistical software.

Regards

Loukas]]>

How can I calculate variance and mean?

Thanks]]>

I'm carrying out a research which tries to analyse factors affecting coffee consumption behavior, there are 7 independent variables on hand and 1 dependent variable which is coffee consumption behavior

The data is collected using survey form, handed to 267 respondents (coffee consumers), the 7 given variables as can be seen in the image bellow are placed in the survey form in 7 sections, each section having their own 3-4 statement with 1-5 degree of agreement levels.

It should...

Which test should be used with 1 dependent variable and 7 independent variables?]]>

It reminds me of multilevel...

Panel regression]]>

I'm certainly stressing out in regards to my MSc Thesis right now and I could certainly use your help.

I am testing a IS success model. It consists of 9 constructs. I did a multiple regression analysis for all expected significant correlations (according to theory). The whole model and the regression analysis look like this:

However, after this went fine (according to my opinion) I now need to do a hierarchical regression analysis (i think, to see...

Hierarchical Regression]]>

Let us assume I know other data about the gold standard positive and negative cases (continuous variables such as patient age, temperature)

What tests can be used to interpret the differences in the new test and the gold standard? Should I compare these variables (age, temp) of TP vs FP? Or must I compare all of TP vs FP vs FN vs TN?

Thanks!]]>

is there any trick to get 100 samples from the population in one go in spss?]]>

I hope you can help me to answer the following questions

""Do people consider magazines credible when they take a purchase decision?"" How can I transfer this question into a hypothesis? What will be considered as the independent variable (X) and the dependent variable (Y)?]]>

I am new to statistics here. Currently, I am assessing the effect of aeration system on water quality in aquaculture ponds. I had 3 treatments (a,b,c) with 11 water quality parameters. However, these water quality parameters are measured on daily, every 5 day and weekly basis.

Daily: DO, pH, temperature

Every 5 day: Alkalinity, TAN, NO2-N, NO3-N, PO4-P

Weekly: Turbidity, SS, TSS

I am using SPSS one-way ANOVA analysis to analyze these parameters.

1) Should I separate these...

Need help on one-way ANOVA (SPSS) for Water Quality Analysis]]>

i want to compare male and female adults kinematics while normal walking and perturbation. I do 2x2 anova. The example graph is below. Both effects (gender and perturbation occurance) are significant but interaction is not. How can I get exact information where exactly are statistically significant informations? Can I do post hoc test for interaction If interaction is not significant? I read many different posts and I am very confused now so I would be grateful for claryfying this...

2x2 anova, no interaction]]>

Regards]]>

I'm in the middle of a career change right now and i'm my early 30s. I don't have any family responsibilities and am very flexible. I love my major and am very excited that i have accumulated knowledge in my programming skills (R, SAS, SQL) and acquired different type of analyses for my...

Need some career guidance, please.]]>

From what I have read a Two sample (Paired) T-test would be the appropriate statistical analysis to conduct on EACH set of samples.

I also attempted...

Help Understanding Difference Between Statistical Methods]]>

I’m coming here for really advance statistic/probability advice.

I would like to know the probability of a variable TAU_total such as TAU_total=TAU1+TAU2+….+TAU129.

The variables TAUi are independent of each other.

For each one of them, I have a sample of 20,000 values which you can see some examples of their distribution on the histograms in the attachment.

My question is the following: I would like to be able to determine the probability of TAU_total to be superior to a...

Probability of a multiple variables sum]]>

I am new to this forum and would like some help with the interpretation of the following regression. I hope I am in the right place.

lnWaste = +A(lnGDP) +B(lnGDP)2

I have found coefficients for lnGDP= -1.85 and for (lnGDP)2=0.1

Now I am trying to give an interpretation of what would happen to Waste if GDP increases by x%.

I usually report the elasticity easily but I am not sure how to work with this since I have two different values that I should take into account when...

Help with interpreting log in regression]]>

In many documentation I have read that Kaplan-Meier curves followed by logrank test and/or cox models are the most recommended statistical methods to analyse Survival and test for different factors that may impact the Survival.

However, I have also heard that these are suitable if I have many "times" points in the data, but they may not be the best choice when I want to compare at one, two or three times only (let say at t=0 , t=7 days and t= 14days). In many examples with the...

Survival analysis at few dates: glms? logrank? cox ?]]>

For my master thesis I have to analyze a large set of longitudinal data, where company data is remeasured every year. Within these data, not all companies have the same number of measurements, which makes the data unbalanced.

Since longitudinal data comes with dependence within-subject, I cannot use normal OLS regressions. Therefore, I was thinking of doing mixed effect linear and logistic regressions.

However, for my additional analysis I was planning to perform a quantile...

Analyzing longitudinal unbalanced data - mixed effect quantile regression]]>

I have data representing the best steering wheel angles to travel a given trajectory, and I want to estimate the performance of a driver in the same trajectory by comparing his steering wheel angle inputs to the data I have over a short period of time.

I thought of an error analysis, but I want to know the most suited statistical tools to do it.

Thanks in advance.]]>

I have a sample of size 8. Each sample value represents the number of bus arrivals at a bus stop every 15 minutes. But I wanted to apply the chi-square test to verify the fitting with the Poisson distribution. So, for every 15 minute interval, I generated 15 random numbers. So I got a new sample size 120.

The numbers were generated following a uniform distribution. See an example:

I had the following...

Can I increase the sample size by generating random numbers to apply the Chi-Square Goodness of Fit Test?]]>

at the moment I am evaluating a survey and a bit desperate how to proceed.

In my survey, I tested 8 hypotheses by querying a dependent and an independent variable (both scaled Likert) respectively.

Example of one question set: "Have you already noticed the series 'Currently popular on Netflix'? (Likert scale) and "Has this affected your decision making? (also Likert scale)

Now I want to test how strong the influence of the first question is on the second one and so far I am...

Questions about Statistical Evaluation of Likert Scale]]>

For that purpose the complete data set was used to model a group scoring moderate on health value and a group scoring high on health value by subtracting 1 from the mean centered scores on health value and adding 1 to the mean centered scores on health value, respectively (Cohen, Cohen, Aiken, & West...

Z scores + 1]]>

I need help understanding SPSS output for my marketing research final exam. I have attached a picture with what I want to understand.

I want to understand F score, sig value and t score, beta, mean and R2.

I would appreciate if someone can help me to do well on this exam. Thank you

Sasan]]>

I hope someone is able to help me.

For a literature review I have to run a meta-analysis.

I have an experimental group and a control group, often with pre- and post-data but sometimes there are more data points.

For the meta-analysis I downloaded RevMan; I have to fill in the mean and SD for both the experimental group and control group. For the mean I need the mean difference which is pretty easy but I experience difficulty with finding the SD that I have to use (average population...

I need help with my forest plot]]>

I am currently doing a study and as part of it, I have to develop a questionnaire with the following structure: Given a change in "Factor A" how will it affect "Factor B"?. I have realized that I have many factors (and therefore my questionnaire is quite long). Then, I would like to perform a statistical analysis to check if some of these factors are independent so I can eliminate some questions, and therefore reduce the questionnaire's size. For instance, if after an...

How to choose the best statistical analysis]]>

Thanks for taking time to read my post

I have a model that gives multiple predictions, and I need help to find a non-parametric accuracy test for this case. All predictions can be ranked (they have a stability coefficient). Ideally, the test or precedures hould penalize if not the most stable forecast turns out to be correct. Is there a way to introduce some sort of a scoring element?

I will be very gratfeul for any hints]]>

I'm trying to teach myself statistics online @ khan academy and although its a wonderful resource I have no one to turn to for help when I don't understand. I hope someone here might be able to give me some advice.

I've made some questions up myself to try and work out the answer and check it against a simulation i've written in VBA/Excel to really understand it all.

But.... I'm really stuck on working out the probability of picking card #1 with value 6, #2 with value 6 then #3 a...

Card picking dependant probability without replacement - P(6,6,Red)]]>

I have two independent groups a patient and control group who both completed an executive function test and a social cognition test.

I want to look at whether executive function correlated with social cognition.

Should I be running my correlation on the whole sample? or two correlations one on the control group and one on the patient group separately?

Thanks in advance for your help!

Iona]]>

I am currently writing my thesis and am a little confused about the approach.

I am supposed to do a difference in difference estimation combined with propensity score matching.

I think I do understand both methods in a medical Kontext with a treatment and control group. However, mine is a little different.

I am researching the effect of the shutdown of a major online piracy site on sales and piracy. I don't see how I can make a treatment and control group, since the shutdown makes...

Propensity Score Matching and difference-in-difference]]>

So, my question is, how is it that there is no treatment main effect, but post hoc is significant? What does that mean? Also, for clarity, I ran a one-way RM Anova with Dunnetts multiple comparisons.]]>

Here is my question:

I have a 4 groups of subjects (between factor) repeating the same task for 10 times in different blocks (within factor).

I want to analyse differences between groups.

What i did was to perform a 4 x 10 mixed design ANOVA and look at possible main effect of "group" or interaction "group x block"

However, since I expect a linear increase of performance across block, I would like to...

Transform a variable from discrete to continuous]]>

Adjusting for Differential Misclassification]]>

The data:

I have 1000+ subjects each one scanned with a MR 3 times (with different sequence T1, T2 and IR). Each scan yields (after a segmentation) to the 15 volumes of the brain region in study (the brain region has 15 "sections" which volumes' are interesting). I also have age, sex, and other variables of each subject.

The goal:

One of the goals of the project is to do a comparison between the segmentation results coming from 3...

Choosing the Statistical Test (if exists)]]>