#### Venus

##### New Member
A study of the learning effects of repeated trials of a video game by players of different ages is conducted. Twenty eight players ranging in age from 23 to 48 years each played the video game 5 times (one day apart) with their score recorded each time. It is thought that age has an impact on learning of the game.
• INITIALS – initials of the player;
• PLAYER_ID – ID number of the player;
• AGE – age in years of the player;
• TRIAL – the time (or day) which the game was played (1- 5);
• SCORE – the score on the video game (in thousands of points);
The researcher is interested in carrying out an analysis to understand how the variables AGE and TRIAL influence the variable SCORE. It can be assumed that TRIAL is measuring time in days as each trial is separated by one day and that each player recruited has not had any experience with this particular game.
Use the maximum likelihood method of estimation of the parameters for the model being fitted.

Continue your exploratory data analysis by producing two appropriate plots: one with AGE and one with AGEGROUP.
For Plot 1: Score on video game against Age in years for each trial.
For Plot 2: Score on video game against Trial for each Age-group.

1) Why is a linear mixed model being use for this question?
2) Need guide to carry out the step by step analysis for SPSS for linear mixed model to get the plots for plot 1 and plot 2 above.

#### ondansetron

##### TS Contributor
To avoid telling you answers, I like to ask questions that make you find the answer 1) What is a linear mixed model? How is it different from a regular linear model? What are the assumptions needed for each?
2) Worry about this later. Generating output is the easiest part of statistics. Building a good answer to #1 is far more important.

#### Venus

##### New Member
Linear mixed model means that the parameters are linear and covariates are mixed of fixed and random effects?

#### ondansetron

##### TS Contributor
Linear mixed model means that the parameters are linear and covariates are mixed of fixed and random effects?
Can you be more specific?
1) What is it?
2) What does fixed effect mean?
3) What does random effect mean?
4) How is this different from a "regular" linear model?
5) What are the assumptions of a linear model?
6) What are the assumptions of a linear mixed model?