Can A Bell Curve Be Skewed Instead Of A Normal Distribution?

Hi everyone,
I know the purpose of a bell curve in performance management and reward system. My question is: can the bell curve be skewed?
That is to say, instead of using a normal bell curve or normal distribution every year that says 75% are average performers, 10% above average and 15% below average, can a bell curve change shape based on yearly performance, for example 80 are average, 5 are below average and 15 are excellent?
My company uses the standard distribution and then people are "fit" under the curve. However, it seems unusual to me. Shouldn't the bell curve BE DETERMINED by the role of performers rather than the bell curve DETERMINE the role of performers??
Thanks

Namaskar.
From The situation described above, I do not see the situation of bell shaped curve/normal probability curve. The employees are already screened. So in the performance measurement a negatively skewed curve is bound to be obtained- poor performers tapering left side. Percentages are cut ff points and depends upon management decisions. Performance measures determine the curve and not the vice versa.
regards

hi
statistically speaking a bell curve can be skewed but here the problem is not about the shpe of curve or skewness level but company's policy of performance evaluation your company has decided a fixed bandwidth which has forced distribution to rank employees ineither of the three categories and only x % of ppl can belong to each cat.

How can you put the people under standard distribution? They will occupy position on the basis of their performance scores. The performance scores will determine the nature of the curve. You can not manipulate it.
regards

yes why not.....
depending upon..
1, Business Performance
2, Age of your corporate
for ex if you are a statrt up company , depending upon the gestation period you may or may not be profitable ...but most of your guys cld be high performers which will detrmine your +ve skewed curve and vice versa...
you as a compnay need to decide whether you need to have a normal curve or a skewed curve, and accordingly fit people
trust this helps

1.High performers will determine +ve skewed curve is a news to me.
2.I think a company always needs high performers. This is also a news to me that a company may choose low performers too.
regards

hi,
Can anyone please explain me what exactly a bell curve is and its functionality? As a student, I have never come across this concept. A little light on its benefits and drawbacks would also be helpful.
Thank you
Regards,
Vinisha.

Vinisha ji.
Here is the concept.
1. Take the heights of all the girls of your age. Say about 100 girls.
2. Take out a graph paper. In the graph paper X-axis is for inches and Y-axis is for frequencies of girls on each inch. For the frequencies put the points over every inch. Join the points. You will see a bell shaped curve, that is, if you fold the graph on the point of mean, the two halves will fall exactlly on each other. Almost all human characteristics like job performance scores get distributed on a graph like this.
To get the concept please read any elementry book on statistics for behavioural science and go to the chapter on central tendencies, skewness and kurtosis.
regards

Hi Siddiqif,

When you analyze your data if your trend looks like a normal [not skewed] curve, then that means that the performance variations are random and that there is no single factor that affects the performance issue significantly. The curve will be a normal shaped curve, and will not be flat [will have some height]. Thus, a normal distribution of the variations causes a bell shaped curve.

If the analysis reveals a skewed curve, then you are presented with an opportunity to identify high and low performers on either side of the average. The curve will appear as if it has been squashed, to the right or left. Either way, you can see who has done better than others, and zero in on their practices and experiences.

With these kind of tests, all comparisons are relative - e.g., high performance could be one SD above the mean etc. The exact value of the mean will fluctuate and be determined by the data that goes in.

I think your organization has set limits on metrics, like 80% and above is always excellent, 60% and below is always poor and so on. The problem with this is that if your organizations' performance improves with time [which it will in any case], that 80% and above becomes a very poor cutoff, and should be upgraded to 90% or something like that.

The true use of this curve is to compare performance over time. I would suggest that you get your people together, show them the results and do the same after a month so they can compare and see what you are trying to do. This improvement is what the management will want, rather than arbitrary metrics and numbers.

My Rs.02/two cents.

Thanks Vadivelu,
That gives me something to think about and clarifies the issue. I think the problem is the use of the bell curve.
we are using a performance management system, but as far as i can identify, the bell curve is used more for rewards and increments than to identify the weak & strong performers and their development plans.
What other ways are there to identify strong performers vs weak?