Employee Performance evaluation and Statistics

HR Managers typically insist on 'normalizing' performance ratings such that 10% on band 1, 20% band 2, 40% band 3, 20% band 4 and 10% band 5 etc. This is typically applied recursively to the entire organization (team, dept, organization). This normalization is based on the claim that performance of people follows 'normal distribution'.

There are two flaws in this.

a) Performance of people need not follow 'normal distribution'. Normal distribution occurs when the variation is due to randomness (or chance). Consider two scenarios - one person taking the same test (rather similar test with same pattern) multiple times, and different people takes the same test. One person takes same test multiple times follows normal distribution, as the variation is due to randomness. However different people taking same test may not follow normal distribution. When different people takes same test, the variations are due to randomness as well as difference in individual's skill. Variation in skill need not follow normal distribution.

b) According to statistics, when we take samples out of a population (eg: depts of 100 people in an organization of 10000 people), the mean (average performance) of the samples (individual depts) should follow normal distribution. However current practice is to enforce individual depts normally distributed with same means. This is mainly because no dept head will be ready to admit that his dept performance mean is less than company mean. That simply means the performce ratings are force fit rather than actual performance.

Shuttle service from city to Bangalore airport

There are Volvo Bus (Vayu Vajra) shuttle service from city to Bangalore International Airport (BIAL). You can find the details at http://www.bmtcinfo.com/site/BSBusServicesDetails.jsp?bsserviceid=1. Click on the route link you think relevant to you, details of the route is mentioned. On the rightside there is button (not very intuitive) clicking you can view a google map with stops marked.

You can download a route list at http://www.bmtcinfo.com/uploads/Files/Vayu_Vajra_route_List.pdf.

At the airport bus terminal (which is just in front of the main entrance), there is route map displayed which is very useful, different routs ard marked in different colour.

Vayu Vajra buses are having ample space for keeping the luggage.

On the whole it is very good service, even though it is expensive (about Rs 150 to the city)

Some keyboard shortcuts for Apple Mac OS X

Here are some keyboard shortcuts for Apple Mac OS X. Very few now. Plan to build as I go (started using MacBook Pro now). May be useful for beginners. I have built this using Google doc and published as html. Is there any way I can publish it such that public can edit it?
Link: http://spreadsheets.google.com/pub?key=t_EbCAybhNOGuNpN3FVFzzQ&single=true&gid=0&output=html

Extension Methods in C#

C# has a nice feature called Extension Methods - You can extend the APIs of an Interface or Class by Extesnsion class and methods.
Please refer to the following link for details about usage ( http://msdn.microsoft.com/en-us/library/bb311042.aspx )
This feature is purticularly useful for extending functionality of Interfaces/classes which are not instantiated by us (for example DataReader which typically goy by SqlCommand.ExecuteReader() )
Assume we want to introduce a method for retrieving values from DataReader even if the value is null in database (by default it will throw exception if we try to read data which is null in database)
We can write the following Class for that (Stolen shamelessly from this Answer by Tommy Carlier on stackoverflow )

static class DataReaderExtension
{
public static string GetStringOrNull(this IDataReader reader, int ordinal)
{
return reader.IsDBNull(ordinal) ? null : reader.GetString(ordinal);
}
}
We can use this as follows:
SqlDataReader reader = command.ExectureReader();
string value = reader.GetStringOrNull(0); // this will not break even if value is null
Without Extension methods to achieve this functionality we would have written wrapper class and implement all unnecessary methods also.

Software Estimation - Overestimation Vs Underestimation

I was reading Steve McConnell's book - Software Estimation. He has discussed about the advantages and disadvantages of Over estimation and under estimation.
Arguments against over estimation - (1) Parkinson's law - work will expand to fill the available time. (2) Goldratt's Student's Syndrome - developers will procrastinate until late in the project and then rush to complete the work.
However I think He missed one important disadvantage of over estimation - Lost opportunity. When we overestimate we are forced to cut off some feature unnecessary or delay the shipping date unnecessary. In either way it is lost opportunity.