G Power Analysis

[RUCHIKA GUPTA]

Respected Sir and group members,

I am struggling with G power to understand the process of knowing the required sample size in case of Multiple regression (using SEM).

In a priori power analysis, does the below table shows the correct results. Even when I change the number of predictors drastically there is hardly any change in sample size. Moreover it shows the sample size only as 89.

Also please suggest if there is any other good method for knowing the required sample size before applying multiple regression.

A priori Power Analysis to compute the required sample size

t tests - Linear multiple regression: Fixed model, single regression coefficient

Analysis:     A priori: Compute required sample size

Input:             Tail(s)                                                    =   Two

                         Effect size f²                                        =   0.15

                         α err prob                                            =   0.05

                         Power (1-β err prob)                         =   0.95

                         Number of predictors                        =   7

Output:         Noncentrality parameter δ                =   3.6537652

                         Critical t                                                =   1.9896863

                         Df                                                           =   81

                         Total sample size                                =   89

                         Actual power                                       =   0.9505436

Thank you

Regards

Ruchika