STATISTICS

Statistics



Statistics

Estimation of the Effect Size

The proportion of variance (PV) (R2)(r2):

There are common indices of strength of association in the correlation between the independent variable and the dependent variable. Table 3.6 provides us the subsequent effect size for each proportion of variance.

A study conducted by Steven Z, et al, provides the following information. The variance for the experimental group is 92.8; therefore, the standard deviation was 9.6. The mean of the same experimental group was 8.6, whereas the mean of control group was 13.5.

Applying the formula of effect size in the above data, we get:

ES = M1 - M2 / SD,

ES = 13.5 - 8.6 / 9.6 = 0.51

The procedure

The procedure will become very straightforward, if there is already treatment versus control group data on the dependent variable of interest. the proportion of the control group and the proportion of the treatment group will needed to be determined above the success threshold set on that dependent variable.

I found in one study, the evidence that patients treated are likely to be clinically significant improvements in the FABQ (> 4 - Reduction of points) for 4 months. In this case, the degree of connection between the dichotomous variable, the group (treatment versus control) and the dichotomous dependent variable (success or failure) are tested. In this study we found that the percentage of success in the experimental group was 61% and 42% in the control group.

Power relations in this above situation, can be determined by the final approach to the use of an index effect size based on the difference between "success" experimental relationships compared with the control group. To achieve the desired size of the effect of the ratio is calculated to be processed by arcsine transformation, as shown in Table 4.1. The arcsine transformation of 61% and 42% is 1.793 and 1.410 respectively. The only difference of these values results in the effect size that is 0.383.

Mean of the Control Group

The appearance of the magnitude of the effect in terms of the degree of success is to a control group means to create, such as the success of the threshold of interest. I found from the previous study that the average of the control group was 13.5. On the basis of which an estimated 65 years, a reasonable degree of success for the group, thus avoiding the fear-based intervention in physical therapy. Thus, 65% in the experimental group were above ...