Categorical Data-র বর্ণনা

স্লাইড ১

Describing Categorical Data

স্লাইড ২

How many, out of how many?

A categorical column cannot be averaged. The session starts from that fact rather than from a list of percentages to memorise.

স্লাইড ৩

What you will be able to do at the end of today

স্লাইড ৪

Act I · Counting, and the Three Things It Turns Into

স্লাইড ৫

Four words, and they are not synonyms

Count, proportion, percentage, and rate get used as if they were the same sentence. They are not. The rest of the afternoon is about keeping the denominator in the sentence so the word you print still means something.

স্লাইড ৬

Prevalence needs a place and a time

A prevalence is a proportion with an address. ‘Hypertension is 18.7%’ is not yet a finding. ‘Among these adults, in this district, in these years’ is.

স্লাইড ৭

Missing values, worked

স্লাইড ৮

Collapsing categories is the same trade as a threshold

স্লাইড ৯

An order without a distance

স্লাইড ১০

Act II · Out of How Many? The Question the Number Does Not Answer

স্লাইড ১১

One table, two denominators, one row header between them

স্লাইড ১২

Percentages inside subgroups

স্লাইড ১৩

The same 44.5%, in two sentences

স্লাইড ১৪

Both sentences are worth saying, and they are for different people

স্লাইড ১৫

Where the denominator usually goes missing

স্লাইড ১৬

A percentage of a small denominator is mostly noise

স্লাইড ১৭

Act III · Two Columns at Once, and the Three Percentages in Every Cell

স্লাইড ১৮

Crossing two categorical columns

স্লাইড ১৯

One cell, three percentages, all of them correct

Row, column, and overall: three different denominators, three true percentages, three different sentences. The question is never ‘which number is right?’ It is ‘which sentence were you trying to say?’

স্লাইড ২০

So which percentage do you print?

স্লাইড ২১

The footnote that decides the sentence

স্লাইড ২২

You already read a table this way: sensitivity and specificity

স্লাইড ২৩

Act IV · When the Comparison Is Not a Fair One

স্লাইড ২৪

The crude number and the stratum numbers disagree

Hospital A looks safer until you notice who was sent there. A crude percentage can reverse once the same patients are compared inside the same stratum. That is not a trick. It is why a Table 1 is read before a headline.

স্লাইড ২৫

What a reversal does, and does not, license

স্লাইড ২৬

Comparing two populations as if they had the same patients

Standardization is not advanced material smuggled into description. It is the move that lets two percentages talk to each other when the people underneath them are not the same mix.

স্লাইড ২৭

Did hypertension rise, or did Bangladesh get older?

The crude figures move. The obvious objection is age. The session answers it in one sum, with the standardized figures computed in the room, so a rising headline has to survive a fairer comparison.

স্লাইড ২৮

Comparing a percentage with somebody else’s

স্লাইড ২৯

Act V · What a Percentage Hides, and How to Check

স্লাইড ৩০

Reading a Table 1, in order

স্লাইড ৩১

Auditing a table before you believe it

স্লাইড ৩২

A percentage on its own is a claim with the evidence removed

The session closes on a habit, not a formula. If the denominator is not in the sentence, the number is not finished. That habit is what Session 3.5 then makes you produce yourself.

স্লাইড ৩৩

The same percentage, from three different studies

স্লাইড ৩৪

Common traps, collected

স্লাইড ৩৫

Close

স্লাইড ৩৬

Before the next session