[R-sig-ME] sample size in glmer model
@ouhey|@@ghebghoub @end|ng |rom gm@||@com
Thu Jan 23 12:03:22 CET 2020
Thank you Thierry,
I was mistaken I have 2968 observations (2 Time × 53 participants × 28
Is that enough for 7 parameters?
Do I have room for more interactions ( i would later do a backward
On Thu, 23 Jan 2020 at 10:39, Thierry Onkelinx <thierry.onkelinx using inbo.be>
> Dear Souheyla,
> Your fixed effects need 4 parameters: intercept, V1, TimeLevel2 and
> (Time|Participant) needs 3 parameters: variance of TimeLevel1, variance of
> TimeLevel2 and their covariance.
> The same goes for (Time|Item).
> So you're using 10 parameters.
> (Time|Participant) tries to estimate the difference between two times for
> each participant. Such random effect requires much more information than
> (1|Participant). In this case I'd recommended that you have 10 or more
> observations for the majority of the Time/Participant combinations.
> Best regards,
> ir. Thierry Onkelinx
> Statisticus / Statistician
> Vlaamse Overheid / Government of Flanders
> INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE AND
> Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
> thierry.onkelinx using inbo.be
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> To call in the statistician after the experiment is done may be no more
> than asking him to perform a post-mortem examination: he may be able to say
> what the experiment died of. ~ Sir Ronald Aylmer Fisher
> The plural of anecdote is not data. ~ Roger Brinner
> The combination of some data and an aching desire for an answer does not
> ensure that a reasonable answer can be extracted from a given body of data.
> ~ John Tukey
> Op do 23 jan. 2020 om 11:15 schreef Souheyla GHEBGHOUB <
> souheyla.ghebghoub using gmail.com>:
>> Morning Ben,
>> I am not doing (item|Participant).
>> V1 is a duration (continuous) , I should have an interaction of Time of
>> levels : score ~ V1*Time + (Time|Participant) + (Time|item) ,
>> This means I have 7 parameters including intercept (4 random effects +
>> intercept + V1 + TimeLevel1).
>> I have 1484 observations and 53 participants. The rule is 10 per
>> My question: Is it 10 participants per parameter (i.e. I am allowed 5
>> parameters) or 10 observation per parameter (I am allowed 148
>> I guess it is likely per participant, and if its the case, then should I
>> still report results even the power is less (53 divided by 7 = I have 7.5
>> participants per parameter, not 10 as recommended)
>> Thats all
>> Thank you,
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