Sample size determination for evaluating drip irrigation systems

I. Pai Wu, J. M. Irudayaraj

Research output: Contribution to journalArticlepeer-review


An equation for determining all emitter flows within a submain unit was developed based on the dimensionless energy gradient curve and energy changes due to slope conditions. A computer simulation model was also developed for determining emitter flows along a single lateral line or a submain unit. The simulation model was developed to randomly select emitter flow samples for field evaluation purposes. The simulation results show that the variation of calculated coefficient of variation of emitter flow, VT, using different sample sizes can be present by statistical confidence limits for samples taken from a normal distribution. The distribution of VT for a fixed sample size was also found to be normally distributed. The simulation results indicate that a maximum difference of +36% for the coefficient of variation can be expected when a sample size of 18 is used. This difference can be decreased to ±20% if the sample size is 54 or a mean value of 3 groups of 18 samples is used.

Original languageEnglish (US)
Pages (from-to)1961-1965
Number of pages5
JournalTransactions of the American Society of Agricultural Engineers
Issue number6
StatePublished - Nov 1989
Externally publishedYes

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)


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