Inferential Statistics

Patrick claims that he can achieve a score of at least 215 in bowling. Write the null and alternative hypotheses and state which hypothesis represents the claim.

• H₀: μ ≤ 215

  H_a: μ > 215 Claim

• H₀: μ = 215 Claim

  H_a: μ ≠ 215

• H₀: μ ≥ 215 Claim

  H_a: μ < 215

• H₀: μ ≤ 215 Claim

  H_a: μ > 215

A study comparing the response time of a customer service representative with the amount of experience of the representative revealed a correlation coefficient of 0.916. Assuming 15 degrees of freedom, calculate the test statistic and test this correlation coefficient at the 5% level.

• t = 8.23; there is a significant correlation

• t = 8.84; there is not a significant correlation

• t = 8.84; there is a significant correlation

• t = 8.23; there is not a significant correlation

A p-value of P=0.05 means

• there is a 0.05% probability the results are due to chance

• there is a 0.5% probability the results are due to chance

• there is a 50% probability the results are due to chance

• there is a 5% probability the results are due to chance

Which test is used for correlations?

• Mann Whitney U

• Spearman's Rho

• Wilcoxon T test

• Chi Squared

We asked students whether they liked the course and whether they like mathematics. The we performe a chi-square test of independence. What can we conclude?

• Students who like mathematics like also the course

• We cannot reject the nullhypothesis

• There is no dependence between liking the course and liking math

• Students who hate math like the course

Our observation is -2, the mean 1 and the standard deviation 2. What is the Z score of the observation?

• -1

• 1

• 0

• -1.5

The weight of all students has mean of 65 and a standard deviation of 10. We sample 100 students. What is the (approximate) probability that the sample mean is larger than 65?

• 0

• 5%

• 25%

• 50%

Alexander has computed 2000 confidence intervals with confidence level of 95% in his life. How many confidence intervals did not include the true parameter?

• approximately 0

• approximately 5

• approximately 50

• approximately 100

We compute a test with significance level 5%. How large is the probability of type 1 error?

• approximately 0%

• approximately 5%

• approximately 95%

• It depends on the test

We measure the height of father and sons (in inch) and apply a two sample t-test. What can we conclude?

• Father and sons are approximately equally large

• There is a significant difference in the height of father and sons

• The difference in height of father and sons is 8 inch

• We cannot reject the nullhypothesis