Stat Computing > MLwiN > FAQ

Frequently Asked Questions about MLwiN
How do I use the MLwiN command interface?

Historically speaking, preceding to MLwiN, there was MLn, a DOS based program for multilevel modeling. MLwiN's major improvement on MLn is its graphical user interface. It also keeps a Command interface through Data Manipulation menu for users to issue commands as in MLn. The Command interface will update other screens of MLwiN interactively through the commands issued.

Let's first enter some data into MLwiN. We rename the three variables to be id, sex and score. Click here for more detail on how to rename a variable.

• Open Command interface
  From Data Manipulation menu, select Command interface.

• See what has happened
  The above Command interface window seems very bare, because we have not issued any command from it yet. But we actually can see what has happened since MLwiN started.  Everything that is done through point-and-click is actually translated into command(s) and these commands are echoed back to Command interface window. if we uncheck the box for user, the Command interface window will reveal all the commands that have been issued. For example, we see all the commands including some system commands below. The EDIT command corresponds to the creating of our small data set and NAME command  corresponds to the rename of the three variables.

  WAIT 0
  init  5  1000  400  150  20
  track c90 c91
  prior c92
  GALLfilter c95
  echo 0
  fpath C:\Program Files\MLwiN1.10\discrete
  prefile pre
  postfile post
  EDIT  1 c1  1
  EDIT  2 c1  2
  EDIT  3 c1  3
  EDIT  4 c1  4
  EDIT  5 c1  5
  EDIT  6 c1  6
  EDIT  7 c1  7
  EDIT  1 c2  1
  EDIT  2 c1  0
  EDIT  2 c2  0
  EDIT  3 c2  1
  EDIT  4 c2  1
  EDIT  5 c2  0
  EDIT  6 c2  0
  EDIT  7 c2  0
  EDIT  1 c3  89
  EDIT  2 c3  71
  EDIT  3 c3  68
  EDIT  4 c3  45
  EDIT  5 c3  76
  EDIT  6 c3  39
  EDIT  7 c3  81
  NAME C3  'score'
  NAME C2  'sex'
  NAME C1  'id'

• Recall and modify a command
  
  Now let's say we want to change the first observation of variable score from 89 to 100. We can simply recall the corresponding command by clicking  on it and the command will appear at the bottom field of the Command interface window. This bottom field is actually the place to type a command. Now if we change 89 to 100 here and  hit the Enter key, the corresponding entry will be changed to 100.

• Another Example

  Let's say we want to know the mean value for variable score. We can do this through Averages and Correlations from Basic Statistics menu. The content of the output window is shown below. The first line is the command that produces the result. The first four letters are capitalized, because MLwiN only requires the first four letters to by typed. 

  ->AVERage 1 "score" 

                   N     Missing    Mean         s.d.
  score            7         0     68.571        20.951       

  Now we can type a command such as "aver 1 "sex" to get the mean for variable sex instead of going through the point-and-click process.

For more information 

For more information on using MLwiN commands through Command interface window, see the introductory tutorial part from the manual.

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