A psychologist has developed a set of activities which is intended to help children develop better reading skills. In a study of the effectiveness of these activities, one class of second grade children learns with the activities. Another class of second grade children serves as the control and learns without the activities. After some period of time, the reading skills of all of these children were assessed on a scale of 0 to 100. A summary of these data is:

Which of the following, if present, would lead us to believe that the t-procedures were not safe to use here?

Question

A psychologist has developed a set of activities which is intended to help children develop better reading skills. In a study of the effectiveness of these activities, one class of second grade children learns with the activities. Another class of second grade children serves as the control and learns without the activities. After some period of time, the reading skills of all of these children were assessed on a scale of 0 to 100. A summary of these data is: 
  
 Which of the following, if present, would lead us to believe that the t-procedures were not safe to use here?

Accepted Answer

The non-activity group data is highly skewed, and far from Normal.

Answer

The two population distributions being studied are slightly non-Normal.

Answer

Some children learn to read before second grade, and these could be outliers in the data.

Answer

The sample medians and means for the two groups were slightly different.

Groups	n	x-bar	s
(1) Activities class:	18	51.48	11.01
(2) No Activities class:	15	41.52	17.15

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