Question

A researcher conducts an experiment examining the effect of meditation on attention span. A sample of n = 40 people have their attention span measured at the beginning of the study. Then, after a month of meditating for 10 minutes a day, they are measured again. The results of the study are reported as:

"Meditating for 10 minutes a day increased attention span by an average of M = 12 minutes with SD = 7.86. The treatment effect was statistically significant, t (39) = 4.01, p < 0.05."

How can you interpret the T-statistic value of 4.01?

Participants decreased their attention span by 4.01 minutes.

Participants increased their attention span by 4.01 minutes.  

  Participants' attention span was 4.01 times higher than it was at the beginning of the study.

Participants increased their attention span 4.01 times more than would have been expected by chance if the null were true.

Answer 1

it is given that the result of treatment effect is significant means meditation has increased the attention span

because the null hypothesis is rejected and it is given that the treatment effect is statistically significant.

the null hypothesis : it has not increased the attention span

alternative: meditation has increased the attention span

so calculated test statistics = t = 4.01

so p value at t(39 df) with t 4.01 = 0.0001

since p value < 0.05

it means null is rejected]

and concluded that the meditation has increased the attention span

interpretation of t=4.01

participants increased their attention span 4.01 times more than would have been expected by chance if the null were true.