Asign subjects to groups and get a group average

Hi all,

I have a table containing 3 Variables - Subject ID (N = 1026) , Group ID (Total of 457 groups) and IQ score (one for each subject).

What I am trying to do is to

a) get a list telling me the subjects IDs belonging to each group

b) get an average IQ score for each group

Doesn't seem to be that hard of a problem but I am struggling...

Any help would be appreciated!!

Thanks,

Johanna

Answer 1

[Chunru]

% 3 Variables - Subject ID (N = 1026) , Group ID (Total of 457 groups) and IQ score (one for each subject).
N = 1026;
id = randperm(N)';
gr = randi([1 457], [N, 1]);
iq = randi([80 200], [N, 1]);
data = table(id, gr, iq);
head(data)

ans = 8×3 table
    id     gr     iq 
    ___    ___    ___

    505    275     87
    281    403    156
    996    257    187
    695    370    172
    927     60    162
    431    341    143
    561     99     83
    484    271    126

% a) get a list telling me the subjects IDs belonging to each group
gr0 = data.gr(1);           % group to be identified
a = data(data.gr == gr0, :);
head(a)

ans = 1×3 table
    id     gr     iq
    ___    ___    __

    505    275    87

% b) get an average IQ score for each group
groupsummary(data, 'gr', 'mean', 'iq')

ans = 401×3 table
    gr    GroupCount    mean_iq
    __    __________    _______

     2        4          150.5 
     4        2           94.5 
     6        2            119 
     7        2            122 
     8        1            146 
     9        1            107 
    10        1             96 
    11        6            112 
    12        1            124 
    13        2          125.5 
    14        4          106.5 
    17        4         179.25 
    18        1            178 
    19        2            168 
    20        6         119.83 
    22        7         122.14 

[Johanna Popp]

Thank you!!