Sample Size Determination for Medical Device

#1
We will perform design verification on medical device (portable tabletop) intended for diagnostic purposes. Looking for sample size rational to perform the functional/performance characteristic challenges for design verification purposes. Below is a statistical rational I'm proposing. Looking for feedback if this rational is justifiable. If not, what would appropriate statistical rational.
Is this sample size rational valid for reusable capital equipment?
Can I divide number of trials or samples into multiple devices?

"Using the Binomial distribution to calculate the sample size at 95% confidence the probability to detect no more than zero defect present out of 95% of the population would require at-least 59 number of trials or samples. Since the device is reusable capital equipment the number of trials will be divided into three devices where each device will perform 20 trials with total of 60 trials. This will discover any inherit risk present in the device. The device gets 100% functionally tested during manufacturing."
 

yodon

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#2
What is the intended user / patient population? Can different users / patients (age, weight, sex, race, ...) have any effect? What kind of tests are these? Mechanical, performance, etc.? That might have a bearing. Are you saying that only 3 devices will be used, with each undergoing 20 tests?

Sorry I can't answer your question but maybe this will help stimulate discussion.
 
#4
What is the intended user / patient population? Can different users / patients (age, weight, sex, race, ...) have any effect? What kind of tests are these? Mechanical, performance, etc.? That might have a bearing. Are you saying that only 3 devices will be used, with each undergoing 20 tests?

Sorry I can't answer your question but maybe this will help stimulate discussion.
Hi Yodon, yes this would be 3 devices each undergoing 20 tests vs. producing 60 units to collect data from 1 trial with each device. Do you think it would be valid to perform multiple trials across 3 units to collect the 60 trials worth of data for design verification testing (mechanical and performance testing)?
 

Bev D

Heretical Statistician
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Super Moderator
#5
In my organization we manufacture diagnostic instruments so we a similar dilemma.
we calculate the required sample size as the number of runs necessary (n) on a single instrument.
and because performance isn't homogenous across instruments we use run that sample size (n) on multiple instruments (k).

we find that this is much more informative
 
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