New Grads for your Project

---

If you recruit new grads for your project, I wonder if your experience comports with this report from "Intelligent"? The gist seems to be this:

• Headline: "1 in 6 Companies Are Hesitant To Hire Recent College Graduates"
• 75% of companies report that some or all of the recent college graduates they hired this year were unsatisfactory
• Hiring managers say recent college grads are unprepared for the workforce, can’t handle the workload, and are unprofessional

I'm thinking there may be more troubles in established firms than in more "flexible" start-ups, but here's Intelligent's observation:

“Many recent college graduates may struggle with entering the workforce for the first time as it can be a huge contrast from what they are used to throughout their education journey. They are often unprepared for a less structured environment, workplace cultural dynamics, and the expectation of autonomous work. Although they may have some theoretical knowledge from college, they often lack the practical, real-world experience and soft skills required to succeed in the work environment. These factors, combined with the expectations of seasoned workers, can create challenges for both recent grads and the companies they work for,” says Intelligent’s Chief Education and Career Development Advisor, Huy Nguyen.

Wow! I hope this not true in your industries, but it may be distressingly common.

---

Like this blog? You'll like my books also! Buy them at any online book retailer!

Quantitative Methods: It takes a number!

Numbers are a PM's best friend

Bayes Thinking Part II

---

In Part I of this series, we developed the idea that Thomas Bayes was a rebel in his time, looking at probability problems in a different light, specifically from the proposition of dependencies between probabilistic events.

In Part I we posed the project situation of 'A' and 'B', where 'A' is a probabilistic event--in our example 'A' is the weather--and 'B' is another probabilistic event, the results of tests. We hypothesized that 'B' had a dependency on 'A', but not the other way 'round.

Bayes' Grid

The Figure below is a Bayes' Grid for this situation. 'A+' is good weather, and 'B+' is a good test result. 'A' is independent of 'B', but 'B' has dependencies on 'A'. The notation, 'B+ | A' means a good test result given any conditions of the weather, whereas 'B+ | A+' [shown in another figure] means a good test result given the condition of good weather. 'B+ and A+'  means a good test result when at the same time the weather is good. Note the former is a dependency and the latter is a intersection of two conditions; they are not the same.

  

The blue cells all contain probabilities; some will be from empirical observations, and others will be calculated to fill in the blanks. The dark blue cells are 'unions' of specific conditions of 'A' and 'B'. The light blue cells are probabilities of either 'A' or 'B'.

Grid Math

There are a few basic math rules that govern Bayes' Grid.

• The dark blue space [4 cells] is every condition of 'A' and 'B', so the numbers in this 'space' must sum 1.0, representing the total 'A' and 'B' union
• The light blue row just under the 'A' is every condition of 'A', so this row must sum to 1.0
• The light blue column just adjacent to 'B' is every condition of 'B' so this column must sum to 1.0
• The dark blue columns or rows must sum to their light blue counter parts

Now, we are not going to guess or rely on a hunch to fill out this grid. Only empirical observations and calculations based on those observations will be used.

Empirical Data

First, let's say the empirical observations of the weather are that 60% of the time it is good and 40% of the time it is bad. Going forward, using the empirical observations, we can say that our 'confidence' of good weather is 60%-or-less. We can begin to fill in the grid, as shown below.

In spite of the intersections of A and B shown on the grid, it's very rare for the project to observe them. More commonly, observations are made of conditional results.  Suppose we observe that given good weather, 90% of the test results are good. This is a conditional statement of the form P(B+ | A+) which is read: "probability of B+ given the condition of A+".  Now, the situation of 'B+ | A+' per se is not shown on the grid.  What is shown is 'B+ and A+'.  However, our friend Bayes gave us this equation:

P(B+ | A+) * P(A+) = P (B+ and A+)  = 0.9 * 0.6 = 0.54

Take note: B+ is not 90%; in fact, we don't know yet what B+ is.  However, we know the value of 'B+ and A+' is 0.54 because of Bayes' equation given above.

Now, since the grid has to add in every direction, we also know that the second number in the A+ column is 0.06, P(B- and A+).

However, we can go no farther until we obtain another independent emprical observation.
 

To be continued

In the next posting in this series, we will examine how the project risk manager uses the rest of the grid to estimate other conditional situations.

Share this article with your network by clicking on the link.

 

---

Like this blog? You'll like my books also! Buy them at any online book retailer!

Bayes thinking, Part I

---

---

Our friend Bayes, Thomas Bayes, late of the 18th century, an Englishman, was a mathematician and a pastor who's curiosity led him to ponder the nature of random events.

There was already a body of knowledge about probabilities by his time, so curious Bayes went at probability in a different way. Until Bayes came along, probability was a matter of frequency:

"How many times did an event happen/how many times could an event happen". In other words, "actual/opportunity".

To apply this definition in practice, certain, or "calibrated", information is needed about the opportunity, and of course actual outcomes are needed, often several trials of actual outcomes.

Bayes' Insight
Recognizing the practicalities of obtaining the requisite information, brother Bayes decided, more or less, to look backward from actual observations to ascertain and understand conditions that influenced the actual outcomes, and might influence future outcomes.

So Bayes developed his own definition of probability that is not frequency and trials oriented, but it does require an actual observation. Bayes’ definition of probability, somewhat paraphrased, is that probability is...

The ratio of expected value before an event happens to the actual observed value at the time the event happens.

This way of looking at probability is really a bet on an outcome based on [mostly subjective] evaluations of circumstances that might lead to that outcome. It's a ratio of values, rather than a frequency ratio.

Bayes' Theorem
He developed a widely known explanation of his ideas [first published after his death] that have become known as Bayes' Theorem. Used quantitatively [rather qualitatively as Bayes himself reasoned], Bayesian reasoning begins with an observation, hypothesis, or "guess" and works backward through a set of mathematical functions to arrive at the underlying probabilities.

To use his theorem, information about two probabilistic events is needed:

One event, call it 'A', must be independent of outcomes, but otherwise has some influence over outcomes. For example, 'A' could be the weather. The weather seems to go its own way most of the time. Specifically 'good weather' is the event 'A+', and 'bad weather' is the event 'A-'. 

The second event, call it 'B', is hypothesized to have some dependency on 'A'. [This is Bayes' 'bet' on the future value] For example, project test results in some cases could be weather dependent. Specifically, 'B+' is the event 'good test result' and 'B-' is a bad test result;  test results could depend on the weather, but not the other way 'round.

Project Questions
Now situation we have described raises some interesting questions:

• What is the likelihood of B+, given A+? 
• What are the prospects for B+ if A+ doesn't happen? 
• Is there a way to estimate the likelihood of B+ or B- given any condition of A? 
• Can we validate that B indeed depends on A?

Bayes' Grid
Curious Bayes [or those who came after him] realized that a "Bayes' Grid", a 2x2 matrix, could help sort out functional relationships between the 'A' space and the 'B' space. Bayes' Grid is a device that simplifies the reasoning, provides a visualization of the relationships, and avoids dealing directly with equations of probabilities.

Since there's a lot detail behind Bayes' Grid, we'll take up those details in Part II of this series.

Photo credit: Wikipedia

Like this blog? You'll like my books also! Buy them at any online book retailer!