Statistics 5 Probability and Z-Scores

Example

1. State the hypothesis - early stimulation & mild stress result in increase infant development (eyes open sooner, more rapid brain development, and faster growth)

nAvg wgt of 2 yr olds in population μ = 26 lbs

nNULL (H0) – special handling does not affect infant wgt

nALTERNATIVE (H1) - infants who do not get special handling weigh less than 26 lbs

2. Use hypothesis to predict sample characteristics

What do you predict as the wgt of the 2-yr olds?

DIRECTIONAL – hypothesize increase in DV (extra handling increases wgt)

NONDIRECTIONAL – no direction in DV (extra handling changes wgt)

3. Collect random sample data - randomly select sample of infants and train parents to provide extra daily handling (do not bias sample with all fat or skinny infants)

4. Compare sample data with predictions - compare X to μ