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#1
05-24-2011
 USMLE Forums Guru Steps History: Not yet Posts: 298 Threads: 45 Thanked 718 Times in 210 Posts Reputation: 728
What is Categorical Data?

Can anyone explain what is meant by categorical data?

I am confused about when to use a t-test versus a chi-squared test. An example would be greatly appreciated!

Thanks

#2
05-24-2011
 Ex-USMLE Forums Staff Steps History: 1+CK+CS+3 Posts: 753 Threads: 106 Thanked 2,204 Times in 466 Posts Reputation: 2252

Categorical data is the data that can be divided into groups and that are not measured in exact numerical data.

For example:
Age groups, educational levels, gender, race, ...etc

Note that the same variable can also be sometimes numerical for example Age, can be categorical if you speak of age groups but it can also be numerical if you speak of the exact age in years for example.

So you need to see what the question is talking about, see if they are grouped data (categorical) or measured data (numerical).
 The above post was thanked by: apx85 (05-24-2011)
#3
05-24-2011
 USMLE Forums Addict Steps History: 1 + CS Posts: 113 Threads: 8 Thanked 89 Times in 61 Posts Reputation: 99

You'll use X2 to test the null hypothesis of no association between the variables.

the type of categorical data most use for this purpose is fractions and proportions.

as a rule of thumb, if you can build a two by two table, you can use X2.

 Tags Biostatistics-Epidemiology

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