
NonDirectional
(twotailed) Techniques
We can answer the question (i.e., we can
test the hypothesis)
"How likely are we to get this sample if the
null hypothesis is true?"
by testesting the null hypothesis stated below:
There are four steps involved in hypothesis testing:
 State the Hypotheses:
 Null hypothesis: No effect for alcohol consumption
on birth weight. Their weight will be 18 grams. In
symbols:
 Alternative Hypothesis: ALcohol will effect birth
weight. The weight will not be 18 grams. In symbols:
 Define the decision method:
 Gather Data:
The two experimenters got these different sets of data:
Experiment 1 
Experiment 2 


Sample Mean = 13 
Sample Mean = 16.5 
 Evaluate Null Hypothesis:
We calculate Z for each experiment, and then look up the
P value for the obtained Z, and make a decision. Here's
what happens for each experiment:
Experiment 1 
Experiment 2 
Sample Mean = 13
Z = (1318)/1 = 5.0
p < .0000
Reject Ho
ViSta Applet 
Sample Mean = 16.5
Z = (16.518)/1 = 1.5
p = .1339
Do Not Reject Ho
ViSta Applet 
ViSta's Report for Univariate Analysis of Experiment
1 Data. 

ViSta's Report for Univariate Analysis of Experiment
2 Data. 

