To examine the relationship between alcohol consumption and birth weight a resea

Question

To examine the relationship between alcohol consumption and birth weight a researcher selects a sample of n = 20 pregnant rats and mixes alcohol with their food for 2 weeks before the pups are born. One newborn pup is randomly selected from each subject's litter and the average birth weight for the n = 20 pups was found to be M=4.1g (SD=0.1g). It is known that the average birth weight for regular rats (without exposure to alcohol) is = 5.6 grams.What statistical test would solve this and would the results be?

Explanation / Answer

We can use a t test to see if the mean of birth weights is altered.

Formulating the null and alternative hypotheses,              
              
Ho:   u   =   5.6  
Ha:    u   =/   5.6  
              
As we can see, this is a    two   tailed test.      
              
df = n - 1 =    19          
              
Getting the test statistic, as              
              
X = sample mean =    4.1          
uo = hypothesized mean =    5.6          
n = sample size =    20          
s = standard deviation =    0.1          
              
Thus, t = (X - uo) * sqrt(n) / s =    -67.08203932          
              
Also, the p value is, as this is two tailed,              
              
p =    4.81877*10^-24          
              
As the Pvalue is very small, we   REJECT THE NULL HYPOTHESIS.          

There is significant evidence that the mean birth weight is different when alcohol is mixed with the food of pregnant rats. Hence, there is a significant relationship between alcohol consumption and birth weight. [CONCLUSION]

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