Bahar Ysr

62 Questions 72 Answers 0 Followers

Questions related from Bahar Ysr

What Should the Y-Axis Represent in a Cubic Spline Plot from a Cox Model?

Hello all, I wanted to create a spline curve to have the independent variable on x axis. Just wondering for y-axis should I calculate the HR(x;x_ref) on the y-axis? like HR(x;x_reference)=...

21 July 2025 1,398 3 View

In Repeated Measures ANOVA: Should Normality Be Checked on Residuals or outcome variable?

Hi All, In repeated measures ANOVA, does the assumption of normality apply to the residuals from the model, or should we assess the normality of the raw outcome data at each level of the repeated...

08 July 2025 3,060 3 View

Mixed model or GEE or Linear regression when many clusters have only one respondent?

Hello All, I ran a mixed-effects model using country (50 countries) as a random intercept. The random intercept for country was statistically significant, and model fit improved significantly(as...

05 May 2025 3,830 2 View

Should I remove an item to improve Cronbach’s alpha when creating a total score?

Hello All, I have a questionnaire with 8 binary questions and 1 Likert-scale and 3 rating question. When I calculate the standardized Cronbach’s alpha for all 12 items together, the alpha is...

27 April 2025 4,591 0 View

Does significance of one category among 5 categories imply the whole variable is a significant predictor in linear regression?

Hello all, I would appreciate if you had any input for my question below that is a bit misleading for me. I have an independent variable with 5 categories, and only one category shows a...

14 April 2025 4,610 5 View

Can I combine a 5-point Likert scale (1–5) with a 1–10 rating question to get a total/average score?

Hello all, I wanted to get a total/average score from combining a 5-point Likert scale (1–5) with three rating questions (1-10). Can I combine? if yes, which method below is acceptable to...

07 April 2025 502 4 View

Should Survey Likert Scales Include Neutral Response?

Hello, I was wondering whether the 5-point Likert scale in the survey includes a neutral option? Thanks, Bahar

03 April 2025 6,442 4 View

Does Block Randomization Eliminate the Need for Adjustment using regression ?

Hello, I was wondering—if I use block randomization, do I still need to adjust for confounders during the analysis phase? I understand that block randomization ensures equal sample sizes across...

23 March 2025 1,823 2 View

How to determine block size for block randomization in an RCT?

Hello all, I'm conducting a power analysis(t-test) for a randomized controlled trial(blinded one) comparing two independent groups. I plan to use block randomization, and I know the block size...

02 January 2025 3,992 0 View

Difference between AUC and DOR(diagnostic odds ratio)?

Hello all, I would appreciate if you could tell me when to use diagnostic Odds ratio(DOR) instead of AUC (Area under the curve)? or when to have DOR along with AUC ? Bahar

23 November 2024 2,370 4 View

Choosing between Confusion Matrix-Based and Prevalence-Adjusted formulas for PPV, NPV, and accuracy?

Hello all, I have a protocol where the researchers used prevalence to calculate PPV, NPV, and Accuracy (using the second set of formulas below). I am considering using the first set of formulas...

20 November 2024 4,122 0 View

What is the difference b/n Retrospective chart review and Retrospective cohort study?

Hello all, Could you please help me to figure out what is the difference between Retrospectives cohort study and Retrospective chart review? any input appreciated

17 November 2024 4,028 3 View

Would a linear mixed model work with this small sample size to compare the two groups?

Hello All, This is a two-arm non-randomized trial with repeated measures. We will recruit 24 participants (~12 per group) over the course of the study. Would a linear mixed model work with this...

24 October 2024 8,207 4 View

How to learn chart review?

Hello all, I am familiar with the systematic review and meta analyze, now I am looking for the resource to learn chart review, could you please help me how to learn that ? Thanks so much

04 October 2024 6,842 0 View

Why a significant p-value does not always correspond to a confidence interval that excludes zero?

Hello All, I can see sometimes The H0 null hypothesis has been rejected using Wilcoxson-sign rank test, in this case I was expected to confidence interval not include zero but it includes. why?...

26 September 2024 2,369 8 View

Can I have sample size calculation for retrospective study, or should I use only a sample of convenience for that?

Hello all, it's common to have sample size calculation for prospective study. I was wondering can I have sample size calculation for retrospective study, or should I use only a sample of...

21 September 2024 3,252 4 View

Negative adjusted R square?

Hello all, I want to assess the effect of one categorical independent variable along with a few confounders on one continuous outcome variable, I fitted a multiple regression and see the adjusted...

10 September 2024 2,913 5 View

How to calculate total score in likert scale?

Hello all, I have 20 patients with the survey, including the Likert scale; I want to have a "Wilcoxson sign rand test" to do comparison for total score not the sub-score; is that correct to say...

28 August 2024 2,781 4 View

One cross over design?

In one crossover study that measures pain at baseline, pre-intervention, and post-intervention, is it correct to compare baseline pain measurements with those from each treatment arm to assess...

28 August 2024 7,274 0 View

Chi-square vs Z-test or proportion test? superiority tests vs non-inferiority tests?

Hi everyone, Is that correct to say; A Chi-Square test is typically used to test for differences in proportions between two or more groups, but it is generally used for superiority tests rather...

27 August 2024 634 0 View

How to figure out a mixed model provide a reasonable fit?

Hello, I am familiar with mixed model, just wanted to know How to figure out a mixed model provide a reasonable fit? when I get the results of running mixed model which criteria should I...

23 August 2024 5,264 3 View

Regression with categorical predictor variable?

Hello, I want to check if the stroke location changed my outcome variable only for right vs left vs both hemispheres. I want to have a regression analyze with the categorical predictor, which is...

22 August 2024 4,235 1 View

Sample size formula for the survey?

Hi All, I am looking for the sample size formula in the survey to include confidence level, margin of error in that. I have also expected response rate, to account for the sample size Thanks, Bahar

13 August 2024 1,950 6 View

How to get the associations of confidence with demographic variables (Likert item and Likert scale)?

Hi ALL, I want to specify the associations of confidence with demographic variables, but I think depending on if confidence is measured using a single Likert-type item or a Likert scale,...

12 August 2024 3,995 3 View

Comparing cause and cause and manner of death b/n the clinical impression and the autopsy findings?

Hello, Which statistical test will be used to compare cause and cause and manner of death b/n the clinical impression and the autopsy findings. Thanks, Bahar

09 August 2024 2,779 4 View

What should I do when P-value in Wilcoxson test doesn't meet my expectation?

Hello, I aim to compare the Length of Stay (LOS) in hours b/n two independent groups, with sample sizes of 300 and 310. The LOS data does not follow a normal distribution and shows right-skewed...

26 June 2024 1,914 7 View

How to get the correlation in repeated measure study?

Hi everyone, I was wondering how to get the correlation between one dependent variable and independent variable, Pearson correlation is not an option as there is a follow up visit for each...

25 June 2024 8,173 6 View

can I use Roc Curve in a pilot study?

Hi everyone, we know that the analysis of pilot studies should be based on descriptive statistics and ideally not involve any inferential statistics (i.e., P values). Based on this can I use Roc...

25 June 2024 4,464 7 View

Difference b/n Pilot study and exploratory study?

The Analyse for Pilot study should be based on the descriptive stat and ideally not involved inferential stat. what about exploratory study? can I do inferential stat like cox regression or...

18 June 2024 5,809 3 View

Should I use XS chart or XR chart in Statistical process chart?

X-S chart will be used for the sample size greater than 10 and XR chart will be used for sample size less than 10, could you please tell me for the below sample size which one is more appropriate?

11 June 2024 2,403 0 View

What is the minimum required number of obs per subgroup to use a p-chart?

Hi everyone, I've created a p-chart to monitor a binary variable on a quarterly basis. But I noticed a p-chart requires at least 20 data points. So, I've shifted to monthly reporting. with this...

07 June 2024 4,945 0 View

What assumption will be used if the assumption of Anova are unmet?

Hi everyone, what assumption will be used if the assumption of one-way Anova are unmet? I think Kruskal Wallis-test, am I right? What about two-way Anova?

04 June 2024 2,296 3 View

Logistic regression with time varying covariate?

I have two outcome variables: 1- binary 2- repeated measure There is only one independent variable which is time varying covariate Iam looking for the article to write the Stat for: 1-...

02 June 2024 9,963 3 View

Can I run Mixed-effect-logistic regression with only one single outcome variable which is time varying covariate?

Can I run Mixed-effect-logistic regression with only one single outcome variable which is time varying covariate?there is no confounder for the study. or should i have more than one independent...

01 June 2024 927 7 View

Considering confounder to compare the outcome variable b/n two independent groups ?

Hi everyone, t-test will be used to compare the outcome variable b/n two independent groups, my question is If I want to consider confounder what stat method is suitable? Thanks

01 June 2024 6,606 1 View

LMM is the option to see how changes in the time varying covariate impact the repeated measure outcome variable?

I have a time varying covariate as an independent variable and outcome variable is a continuous outcome measured at multiple time points, can I say LMM is the option to see how changes in the time...

25 May 2024 1,638 0 View

What Is The lowest sample size to achieve the study objectives?

Hi everyone, I used Cochran’s formula to get the sample size estimation, which is 140, and reviewer asked me what Is The lowest sample size to achieve the study objectives? Could you please...

23 May 2024 3,263 4 View

Should I check normality before running X-chart /XS-chart/XR-chart (SPC chart)?

Hi everyone, Should I check normality before running X-chart /XS-chart/XR-chart ? - I believe for chart no need to check as we assume binomial distribution. but i am wondering should for other...

10 May 2024 502 3 View

Survival analyse or t-test?

Hi everyone, I want to compare the following outcome between two independent groups: anesthesia time time to surgical readiness surgical time, emergence time, and total operating room time...

08 May 2024 8,957 13 View

Can I calculate incidence after inclusion and exclusion criteria?

hi everyone, I have three objectives in the protocol. My first objective is to calculate the incidence of specific illness presentations to the emergency departments. Just to be sure if I have...

07 May 2024 2,261 2 View

Running different sample subgroup within P-chart ?

Hi everyone, I want to Apply Tests for Special Causes in p-chart, but the sample size for each group is different. So I don’t have a fixed UCL and LCL, and I will get the following warning with...

06 May 2024 4,418 0 View

Different size of subgroup in SPC chart?

Hi everyone, I want to Apply Tests for Special Causes in p-chart, but the sample size for each group is different. So I don’t have a fixed UCL and LCL. Just a question can I apply Tests for...

06 May 2024 558 9 View

Dealing with outliers?

Hello everyone, I am calculating the duration from Site Selection to Clinical Start Date for the process map. The duration across all groups ranges from 0 to 70 months, with mean of 5.6 months...

04 May 2024 2,681 4 View

Which control chart of SPC would be suitable for Length of say in hosp?

Hi everyone, I have two columns in my dataset: one for admission date and another for length of stay in the hospital. I plan to analyze this data using an SPC chart, with the data grouped by...

23 April 2024 8,318 1 View

Sample size for logistic regression?

Hello everyone, I have research including two objectives, one of them is to assess the relationship using logistic regression. another one is comparing two groups using Mann-Whitney U...

21 April 2024 5,083 4 View

One way anova?

Hi everyone, I have data available for 4 years. To Compare weight-loss outcomes between the four medication groups for whole years, I will apply one-way ANOVA. but I will be asked to compare...

19 April 2024 463 3 View

Is ecological study descriptive or analytic?

Hi Everybody, I have a presentation regarding observational study, I have divided like: Descriptive Study: Analytical study case report/case series...

08 April 2024 5,265 4 View

Can i apply time series in repeated cross-sectional study?

Hi everyone, I would appreciate to guide me on this? I have the study design as a serial cross-sectional study with ten years of data, the goal is: to Identify changes in the workload of...

19 March 2024 1,842 4 View

Competing risk analyze with time varying covariate?

I am wondering is it straightforward to run a competing risk analyze with time varying covariate in SAS or is it complex? is there any Resurce about that? Thanks

17 March 2024 1,890 0 View

Justification for the sample size?

Hi everyone, I have prospective study; the aim is to apply multiple logistic regression. The sample size for the current study is determined based on the previous study. A study designed to...

13 March 2024 2,481 5 View

Multiple anova test?

I have the survey among three groups of health professionals to answer the survey. The survey is a Likert scale for seven different treatment options across different disease conditions (6...

11 March 2024 9,851 3 View

Am I correct to say the only way is descriptive statistics when there is not an independent variable??

Hi everyone, I would appreciate to give me your thoughts/suggestions on my goal: I have a survey on below question, The question is How important do you think it is for residents to learn about...

01 March 2024 4,454 1 View

Does Backward elimination work to identify potential factor?

Hi everyone, I would be appreciative if you could give your suggestion on my goal: My goal is : To determine the factors that can predict Anxiety disorder(AD) and Quality of life(QOL) in the...

01 March 2024 3,758 0 View

Does multiple regression work for my goal?

Hi everyone, I would appreciate to give your suggestion on this goal: To investigate the impact of anxiety disorder on school functioning and social interactions (two subscales of PedsQL). I...

29 February 2024 3,059 0 View

Anova or t-test?

Hi everyone, I would appreciate to tell me you suggestion: I’m going to compare just two independent group. The outcome variables are continuous -one of them has 5 subclass and another one has 4...

29 February 2024 9,027 8 View

How to Identify the risk factors that contribute to risk of surgical complications?

Hi everyone, I would appreciate if you could give me your suggestion/thought on this goal: My goal is to Identify the key variables that contribute to risk of surgical complications in specific...

01 January 1970 1,459 0 View

Negative adjusted R square?

Hello all, I want to assess the effect of one categorical independent variable along with a few confounders on one continuous outcome variable, I fitted a multiple regression and see the adjusted...

01 January 1970 3,046 11 View

Comparing trt with baseline in one cross over design?

Hello all, I have one cross over design, two different treatment A and B and two different period including one wash out period. There is only one sequence. The measurement is like...

01 January 1970 774 0 View

How to determine block size for block randomization in an RCT?

Hello all, I'm conducting a power analysis(t-test) for a randomized controlled trial(blinded one) comparing two independent groups. I plan to use block randomization, and I know the block size...

01 January 1970 3,246 0 View

Linear mixed model or GEE or Linear regression when many clusters have only one respondent?

Hello All, I ran a linear mixed model (LMM) with country (55 countries) included as a random intercept. The random intercept for country was statistically significant, and the model fit improved...

01 January 1970 4,339 6 View

Does significance of one category among 5 categories(ordinal) imply the whole variable is a significant predictor in regression?

Hello all, I would appreciate if you had any input for my question below that is a bit misleading for me. I have an independent variable with 5 categories (ordinal), and only one category shows a...

01 January 1970 8,130 7 View

How to deal with high variability in Power analysis?

Hello, The researcher plan to conduct a (RCT) to compare a control group with an intervention group. They have provided a (MCID) for the length of stay (LOS) of one day. However, the standard...

01 January 1970 8,017 2 View