## IQR interquartile range

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## IQR interquartile range

Hello!

I am new to statistics and I was wondering if you could help me.

I have collected weight and height of 80 people, those have performed a test twice. This mean, I have two final scores for each person (160 scores).
With jamovi I got the IQR of weight and height, and I need to understand if these variables could impact the scores. This mean I have to find evidence against the null hypothesis by percentile (25th, 50th, 75th) comparing the scores by height and weight and BMI.

How do I proceed?

ste

Posts: 3
Joined: Sat Sep 01, 2018 6:40 pm

## Re: IQR interquartile range

Hi,

I'm not completely sure what you want to do with the IQR. Could you elaborate on this sentence:
This mean I have to find evidence against the null hypothesis by percentile (25th, 50th, 75th) comparing the scores by height and weight and BMI.

Cheers,
Ravi

Ravi

Posts: 149
Joined: Sat Jan 28, 2017 11:18 am

## Re: IQR interquartile range

Ravi wrote:Hi,

I'm not completely sure what you want to do with the IQR. Could you elaborate on this sentence:
This mean I have to find evidence against the null hypothesis by percentile (25th, 50th, 75th) comparing the scores by height and weight and BMI.

Cheers,
Ravi

Yes, sure!

80 people performed resuscitation manoeuvres on a mannequin. The mannequin elaborates some data such as mean rate (frequency) and mean depth of chest compressions.

In different publications, weight, height and BMI are characteristics able to impact the performance. This is why it's necessary to compare the results (such as mean depth and mean rate) by weight, height and BMI. Weight and height (as BMI) are grouped into IQR and than compared with scores.

You can check out this article: Contri E, Cornare S "Complete chest recoil during laypersons' CPR: Is it a matter of weight?" American Journal of Emergency Medicine, 2017
Attachments
Screen Shot 2018-09-04 at 10.17.15.png (75.23 KiB) Viewed 3021 times
ste

Posts: 3
Joined: Sat Sep 01, 2018 6:40 pm

## Re: IQR interquartile range

Hmm, I wonder why you would want to split your continuous variables into 4 quartile groups and then do separate ANOVA's for each predictor. I might be missing something, but this seems more like a multiple regression to me with weight, height, and BMI as covariates.

Ravi

Posts: 149
Joined: Sat Jan 28, 2017 11:18 am

## Re: IQR interquartile range

Nonetheless, if you want to do this you have to use computed variables at the moment (we are finishing up an easier way to recode variables but it's not completely finished yet). Here's a blog post about computed variables: https://blog.jamovi.org/2017/11/28/jamovi-formulas.html.

You need to use a series of IF statements to recode the continuous variables into quartile labels as follows:
Screenshot from 2018-09-04 11-14-13.png (41.49 KiB) Viewed 3008 times

So you have to use the values you get from the descriptives to recode your variable. Here's the example code:
Code: Select all
`IF(x1 < 4.17, 'Q1', IF(x1 < 5.00, 'Q2', IF(x1 < 5.67, 'Q3', 'Q4')))`

Ravi

Posts: 149
Joined: Sat Jan 28, 2017 11:18 am

## Re: IQR interquartile range

Ravi wrote:Nonetheless, if you want to do this you have to use computed variables at the moment (we are finishing up an easier way to recode variables but it's not completely finished yet). Here's a blog post about computed variables: https://blog.jamovi.org/2017/11/28/jamovi-formulas.html.

You need to use a series of IF statements to recode the continuous variables into quartile labels as follows:
Screenshot from 2018-09-04 11-14-13.png

So you have to use the values you get from the descriptives to recode your variable. Here's the example code:
Code: Select all
`IF(x1 < 4.17, 'Q1', IF(x1 < 5.00, 'Q2', IF(x1 < 5.67, 'Q3', 'Q4')))`