Question

The t-chart only has certain values for degrees of freedom (n=1-30, 40,50,…,120, ∞). If the degrees of freedom you are looking for does not appear on the chart, go to the LOWER value on the chart. For example, if you have 47 degrees of freedom, use the corresponding t-values for 40 degrees of freedom. This is considered a “conservative solution.” Why do you think you would use the LOWER degrees of freedom and not the HIGHER value?

Answer 1

Ans:

As degrees of freedom increases t-distribution approaches a normal distribution.

When degree of freedom is higher,the t distribution is narrower(as it approaches toward normal distribution),so p-value is lower for a t statistic and we will be more likely to reject the null hypothesis.

When degree of freedom is lower,the t distribution is wider,so p-value is higher for a t statistic and we will be less likely to reject the null hypothesis.

e.g.

for t=1.5

if df=10,p-value(one tailed)=tdist(1.5,10,1)=0.0823

if df=12,p-value(one tailed)=tdist(1.5,12,1)=0.0772

So,Lower degree of freedom is considered conservative solution.