Checklists for evaluating study design, statistical analysis, criteria of quality and report of studies in the website  https://www.equator-network.org/reporting-guidelines/:

• Randomised trials: CONSORT
• Observational studies: STROBE
• Systematic reviews: PRISMA
• Study protocols): SPIRIT, PRISMA-P
• Diagnostic/prognostic studies): STARD, TRIPOD
• Case reports): CARE
• Clinical practice guidelines): AGREE; RIGHT
• Qualitative research): SRQR, COREQ
• Animal pre-clinical studies): ARRIVE
• Quality improvement studies): SQUIRE
• Economic evaluations): CHEERS

Calculation of a sample size 

1.      http://www.surveysystem.com/sscalc.htm

2.      http://www.raosoft.com/samplesize.html

3.      http://www.nss.gov.au/nss/home.nsf/pages/Sample+size+calculator

4.      http://www.calculator.net/sample-size-calculator.html

5.      https://www.surveymonkey.com/mp/sample-size-calculator/

6.      https://fluidsurveys.com/survey-sample-size-calculator/

Check plagiarism

https://smallseotools.com/vi/plagiarism-checker/