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Suppose the number of admissions to the emergency room at a small hospital follows a Poisson distribution but the incidence rate changes on different days of the week. On a weekday there are on average two admissions per day, while on a weekend day there is on average one admission per day. What is the probability of at least one admission on a Saturday?

Short Answer

Expert verified
The probability of at least one admission on a Saturday is approximately 0.6321.

Step by step solution

01

Understanding the Poisson Distribution

The problem describes that the number of admissions follows a Poisson distribution. This means the probability of a given number of events (admissions) occurring in a fixed interval of time is described by the Poisson probability mass function: \[ P(X=k) = \frac{e^{-\lambda} \lambda^k}{k!} \]where \( \lambda \) is the average rate of occurrence and \( k \) is the number of occurrences.
02

Identifying Parameters for the Weekend

Since the problem specifies a weekend day (Saturday), we use the average number of admissions for a weekend, which is \( \lambda = 1 \). This will be used to find the probability of zero admissions, as we want the probability of at least one admission.
03

Finding Probability of Zero Admissions

Calculate the probability of zero admissions on a Saturday. Use the Poisson formula with \( \lambda = 1 \) and \( k = 0 \). Substitute into the formula:\[ P(X=0) = \frac{e^{-1} 1^0}{0!} = \frac{e^{-1} \cdot 1}{1} = e^{-1} \]
04

Calculating Probability of At Least One Admission

The probability of at least one admission is the complement of zero admissions. Calculate it as:\[ P(X \geq 1) = 1 - P(X=0) = 1 - e^{-1} \]
05

Final Calculation

Compute the final probability using the value of \( e^{-1} \), which is approximately 0.3679:\[ P(X \geq 1) \approx 1 - 0.3679 = 0.6321 \]

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Probability Calculation
The Poisson distribution is a powerful tool in statistics, used to calculate the probability of a given number of events occurring in a fixed time frame. When we talk about \'probability calculation\', especially in the context of a Poisson distribution, we refer to determining the likelihood of certain outcomes based on an average rate of events, or \( \lambda \), over a set period.
Basically, this probability is calculated using a formula where \( e \) is a constant roughly equal to 2.71828. Here’s a brief rundown:
  • \( P(X=k) = \frac{e^{-\lambda} \lambda^k}{k!} \)
  • \( \lambda \) is the average number of events
  • \( k \) is the exact number of events we want to calculate the probability for
In our case, we wanted to determine the likelihood of zero or more admissions in an emergency room scenario. Specifically, finding out at least one admission implies we need to compute the inverse of calculating zero admissions and use the complement rule: \( P(X \geq 1) = 1 - P(X=0) \).
This step-by-step method helps simplify problem-solving in a real-world context, such as estimating emergency room admissions.
Emergency Room Admissions
Emergency room admissions often offer a glimpse into the unpredictability of real-life occurrences. Through statistical models like the Poisson distribution, we can anticipate the likelihood of events happening over time. This specific situation involves a small hospital experiencing admissions based on type of the day.
There are several reasons why admissions might follow a Poisson distribution:
  • Admissions are independent: Each event (each new admission) does not influence the next.
  • Consistent average rate: Over each weekend, there's the same average number of admissions historically.
  • Fixed time intervals: Admissions are calculated over similar periods (weekends vs. weekdays).
On weekends, the hospital expects, on average, one admission per day. This allows the calculation of probabilities for different numbers of admissions, enabling preparation and resource allocation in hospitals. Understanding these statistical principles equips healthcare professionals to manage resources effectively and prepare for high-admission periods.
Incidence Rate
Incidence rate is a core statistical concept that refers to the average number of occurrences per unit of time in a population. In this scenario, it helps quantify hospital emergency room admissions by expounding on their regular frequency across different days.
For weekdays, the incidence rate is set at two admissions per day, while for weekends it is one admission per day. This data allows healthcare providers to better grasp patterns in admissions and adjust their operations accordingly:
  • Scheduling: Staffing decisions can be more effectively managed when patterns are understood.
  • Supply management: With admissions projected, restock of supplies, medications, and other essentials can be planned efficiently.
  • Strategic planning: Decisions regarding beds and patient handling can be modeled to match demand.
By understanding and actually calculating the incidence rate, healthcare institutions can better manage unexpected spikes in patient arrivals with accuracy and improve patient care dynamics. This proactive monitoring is central to maintaining both quality and operational efficiency in emergency medical situations.

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Most popular questions from this chapter

An article was published [13] conceming the incidence of cardiac death attributable to the earthquake in Los Angeles County on January \(17,1994 .\) In the week before the earthquake there were an average of 15.6 cardiac deaths per day in Los Angeles County. On the day of the earthquake, there were 51 cardiac deaths. What is the maximum number of cardiac deaths that could have occurred on the day of the earthquake to be consistent with the rate of cardiac deaths in the past week? (Hint: Use a cutoff probability of .05 to determine the maximum number.)

What is the probability of obtaining at least 6 events for a Poisson distribution with parameter \(H=4.0 ?\)

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