Skip to main content

Questions tagged [failure-rate]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
6 votes
2 answers
115 views

Compare failure rates across multiple systems

I work in pharmaceutical manufacturing and one part of a process is a filtration step that uses 'clusters' or 'sets' of single-use (disposable) filters in parallel - the product flows into a manifold ...
ChemEnger's user avatar
0 votes
0 answers
16 views

Real-world testing: estimating chance that there's an unknown variable/constraint/relationship

I'm working on a hardware product where reliability is paramount. So, one test I've done is to power-cycle units repeatedly, seeing if they properly start up. Result in 10k power-cycles of a group of ...
Daniel Griscom's user avatar
2 votes
1 answer
98 views

Statistical test for rates that are very low with low count

I want to know if dataset suitable for test of significance, and if 'no' (which I am suspect) why exactly not as I must report it why not. I have three apples species (Gala, Pink Lady and 'new') and ...
lincoln80's user avatar
3 votes
1 answer
44 views

Cumulative Incidence Function given no event before time $t_d$

Suppose we have a simple competing risks model and have a calculated $CIF_K$ for two events $\{k_1, k_2\} \in K$. By definition $CIF_{k_1}(t_i)$ gives us the probability that event $k_1$ has occurred ...
JBB's user avatar
  • 31
6 votes
1 answer
76 views

Compare reliability / lifetimes/ failures of two different groups

I have two different groups of devices with different failure rates: Group 1: 72 devices, 57 % did not fail during observation. Group 2: 11 devices, no device failed during observation. How could I ...
Ben's user avatar
  • 3,473
0 votes
0 answers
9 views

Population reliability based on sample testing [duplicate]

I have a total population of X, and I test Y < X units for a certainly binary reliability test. Of Y units, some y fail the reliability test. Is there a method (oversimplification is ok) that can ...
useyourhoosh's user avatar
0 votes
0 answers
9 views

Comparing roof life of two different population of homes

I am trying to compare the initial roof life of two different data sets of homes. I want to know if the data can be said to show a statistical difference in roof life. I have two populations. One ...
JMS's user avatar
  • 1
1 vote
0 answers
65 views

Calculate failure probability for given time series data

I am trying to find a way to calculate the likelihood that a machine will fail. Specifically, I would like to receive a prediction such as, "There is a 28% chance that this machine will fail ...
mgerbracht's user avatar
3 votes
1 answer
239 views

Relationship between Survival Distributions and Log Linear Regression in Accelerated Failure Time models

The accelerated failure time model (AFT) can be expressed as: $S_{1}(t) = S_{0}(\frac{t}{\gamma})$ where $S_{0}$ is a specified baseline survival distribution and $\frac{1}{\gamma}$ is the accelerant/...
Pete's user avatar
  • 33
1 vote
0 answers
35 views

Confirming that the failure rate of a new component is less than or equal to the failure rate of the old component with 95% confidence

I have a new component that is meant to replace an old component that has a well-documented failure rate. Both components are buttons, and the failure rate corresponds to the mean number of button ...
Ryan Bowers's user avatar
1 vote
0 answers
23 views

Component reliability with an uncertain starting time

I have a lab data analysis challenge which I think can be viewed as a kind of reliability analysis problem. Imagine a warehouse is filled with light bulbs that were installed at some unknown times in ...
kevinkayaks's user avatar
0 votes
2 answers
509 views

95 percentile for failure frequency with Poisson process

I am trying to recreate the stats for 'failure frequency' - in this case the 95 percentile - shown in the attached images below. For one set of failure data there are 27 failures over a cumulative ...
akarich73's user avatar
1 vote
1 answer
95 views

Statistical test on a feature that changes over time

Let me explain my use case with an example. Let's say some phone manufacturer such as apple iphone monitors hardware failure rates. I have a hypothesis that says the latest ios version is resulting in ...
Prasanth Regupathy's user avatar
0 votes
1 answer
133 views

Right censored data

I have some data that is right censored. A study has recorded data for several years and some units have failed and some units have not failed (right censored). Now, some of the units observe a minor ...
JLee's user avatar
  • 843
3 votes
2 answers
82 views

Identify the confidence of the impact of a proposed improvement initiative

Assume I have a manufacturing process that involves a moving train. It has failures of certain types like brakes and steering and also the weather. However, we can not do anything with regard to ...
discipulus's user avatar
4 votes
1 answer
139 views

How do I calculate the probability that some system will survive for some years before some event will occur?

I have a failure rate problem involving structural beams. The scenario is that a set of $n$ structural beams are supporting a weight of $W$ kilograms. For the purpose of simplification, we can assume ...
The Pointer's user avatar
  • 1,992
0 votes
2 answers
141 views

Failure Rate of a Sum of i.i.d Random Variables

Suppose that $X_1, X_2, \ldots, X_n$ are i.i.d. random variables, with failure rate $r(t)$. Suppose $r(t)$ is increasing. Is it true that the sum $X_1 + X_2 + \ldots + X_n$ also has an increasing ...
Harish Guda's user avatar
1 vote
1 answer
28 views

How to apply a t-test for product failure?

Background: I'm trying to determine if there is a difference in the rate of failure between two populations. Population 1 is an engine run on one type of fuel. Population 2 is the same engine run on ...
Jonathan Hay's user avatar
1 vote
1 answer
447 views

Statistical method to study failure rate data

What are the good statistical methods to study failure rates? For example, let's say I manufacture 100 tire models and I sold 3 million units that hit on road. Let's say I have the manufacture date, ...
Prasanth Regupathy's user avatar
0 votes
0 answers
33 views

Basic question about probabilities and frequency

I wonder about the following situations for a while now and can't quite figure out: You play lottery once, you have a certain probability to win. When you play more than once, your probabilities don'...
Ben's user avatar
  • 3,473
1 vote
1 answer
50 views

How can I use life-testing to model actual failures?

I am responsible for a large electricity meter fleet and would like to compare and predict the failures of different types electricity meters from existing data. We have the current number of meters ...
skvery's user avatar
  • 13
0 votes
1 answer
41 views

Is it true that for the Weibull distribution a value of $k$ for $ k > 1 $ indicates that the failure rate increases with time?

When describing the Weibull distribution on Wikipedia, it is claimed, among other things, that "A value of $ k > 1 $ indicates that the failure rate increases with time." However, for $ k > 3 ...
Ad van der Ven's user avatar
1 vote
0 answers
46 views

Is there an example that a probability distribution is having an increasing mean residual lifetime(IMRL) but not a Dreasing Failure Rate(DFR)

It is well known in risk theory that a random variable having a Decreasing Failure rate implies the Random Variable has an increasing mean residual lifetime. However, the converse is not true. Is ...
Preston Lui's user avatar