Question

An engineer designs an improved light bulb. The previous design had an average lifetime of 1200 hours. The mean lifetime of a random sample of 2000 new bulbs is found to have a mean lifetime of 1201 hours. Although the difference from the old mean lifetime of 1200 hours is quite small, the P-value is 0.03 and the effect is statistically significant at the 0.05 level. If, in fact, there is no difference between the mean lifetimes of the new and old designs, the researcher has:________
a. committed a type 1 error
b. committed a type 2 error
c. a probability of being correct, which is equal to the P-value
d. a probability of being correct, which is equal to 1-(P-value)

Answer 1

Answer:

a. committed a type 1 error

Step-by-step explanation:

The correct option is - a. committed a type 1 error

Reason -

Type 1 error occurs  when a true null Hypothesis is rejected

Type 2 error occurs when a false null Hypothesis is accepted

Now,

Let us state that,

The null hypothesis and alternate hypothesis is

H0 : There is no difference between the mean lifetimes of the new and old designs

H1 : There is a difference between the mean lifetimes of the new and old designs

Now,

As there is no difference between the mean lifetimes of the new and old designs.

⇒ The null hypothesis is true.

But p value suggests that null hypothesis should be rejected

∴

We have committed a Type 1 error that is rejecting a true null hypothesis.

So,

The correct option is - a. committed a type 1 error