Question

Spatial perception is measured on a scale from 0 to 10. Two groups of 8th grade children are tested for spatial perception. The students in group 1 were first given a short course on spatial concepts. The students in group 2 received no such instruction. R software was used to calculate descriptive statistics for the two samples. What is the value of the pooled standard error

Answer 1

Pooled Standard Error =0.7157

Explanation:

The missing data is

Mean n Std. Deviation Std. Error

group1 6.89 9 1.269 0.423

group2 5.33 9 1.732 0.577

Standard Error= Std. Deviation / √n

First we calculate pooled standard deviation from the pooled variance formula

Sp²= (n1 – 1)* (s1)² + (n2 – 1) *(s2)²/(n1 + n2 – 2)

= 8*(1.269)² + 8 (1.732)²/ ( 9+9-2)

= 12.882888 + 23.998592/16

=2.3050925

Sp = √ 2.3050925 =1.51825

Pooled Standard Error = Sp *sqrt(1/n1 + 1/n2)

=1.51825 *(0.4714)

=0.7157