This test is an extension of the Chi Square test I blogged of earlier. This is applied when we have to compare two groups over several levels and comparison may involve a third variable. Let us consider a cohort study as an example – we have two medications A and B to treat asthma. We… Continue reading Cochran-Mantel-Haenzel Method with T-SQL and R – Part I
Below is the script to create the table and dataset I used. This is just test data and not copied from anywhere. USE [yourdb] GO /****** Object: Table [dbo].[DrugResponse] Script Date: 6/12/2017 6:45:46 AM ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIERl ON GO SET ANSI_PADDING ON GO CREATE TABLE [dbo].[DrugResponse]( [seqno] [int] IDENTITY(1,1) NOT NULL,… Continue reading Dataset for Cochran-Mantel-Hanzel Test
This post is a long overdue second part to the post on Chi Square Test that I did a few months ago. This post addresses relationships between two categorical variables, but in cases where data is sparse, and the numbers (in any cell) are less than 5. The Chi Square test is to be used when… Continue reading Fischer’s Exact Test – with T-SQL and R
This will be year #9 of sql saturdays in Louisville. Every year (starting with 3rd or 4th), it has been a tradition to do ‘precons’ on Fridays. For those who don’t know – Precons are day long paid trainings by an expert in the subject, held on the friday before the event. We have heard… Continue reading SQL Saturday Louisville precon – interview Andy Leonard
A casual twitter-conversation with Karla Landrum and some other peeps led me down memory lane on older events. Our SQL Saturday at Louisville will be 9 years old this year. We were event #23, in 2009. SQL Saturdays started two years before, in 2007. Our first event was held at a training center – 2 tracks,… Continue reading SQL Saturdays – down memory lane
When I was on SQLCruise recently – Buck Woody (b|t) made a interesting statement – that in a room of 23 people, there is over a 50% chance that two or more have the same birthdays. And sure enough, we did end up having more than two people with same birthday. I was tempted to… Continue reading The Birthday Problem – with T-SQL and R
In the previous post I demonstrated the use of binomial formula to calculate probabilities of events occurring in certain situations. In this post am going to explore the same situation with a bigger sample set. Let us assume, for example, that instead of 7 smokers we had 100 smokers. We want to know what are… Continue reading Normal approximation to binomial distribution using T-SQL and R
