- CFA Exams
- CFA Level I Exam
- Study Session 3. Quantitative Methods (2)
- Reading 11. Hypothesis Testing
- Subject 10. Hypothesis Tests Concerning Mean Differences (Paired Comparisons Test)

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**CFA Practice Question**

If a researcher was conducting a paired difference experiment for a sample size of 100 with a 90% confidence interval, which of the following test statistics would he/she use for a two-tailed test?

A. z

_{0.05}= 1.645B. t

_{0.05}= 1.66C. z

_{0.1}= 1.28###
**User Contributed Comments**
6

User |
Comment |
---|---|

mtcfa |
It has to be B since a paired comparison test requires a t-table. |

cfaeater |
So we use the t-table, then look at 120 df (as this is the closest to 100 in the df column), then look down the .10 significance column for a two tailed test and come to 1.658? Are we all in agreement? |

homersimpson |
oh t table ... |

thanhb91 |
The book suggests that we use z only if population variance is known; otherwise, use t for small and large sample. Z can be use as an alternative when sample size is large (>30) |

Emanco |
Since we don't have the standard deviation, directly we choose the t statistic. |

nmech1984 |
Guys z or t or x table is not provided when you are examed. |