1. Estimation Lesson 3 Aims:
• To be able to decide which distribution to use when constructing
a C.I.
• To practice exam style questions.
• To be able to calculate the unbiased estimates for the mean and
variance.

2. Assumptions or Theory for
Summary table of which CI formula to use
Parent
Distribution
Variance
Assumptions or Theory for
C I
Normal
X~(µ,σ2)
Known
Not normal
Unknown
Unknown
Note: If sample is < 30 and not from a normal distribution we can’t use either the z or t distribution to model the situation

3. Unbiased Estimates of the Mean & Variance
The unbiased estimate of the mean from a sample is calculated using:
The variance if unknown can be calculated by using the formula below and we call it s2 rather than σ2

4. Jan 08 Exam Question 6 mins have a go! of Nadal’s of Nadal’s
on Nadal’s

5. Complete relay race
Do revision Exercise page 107. Qu 1 to 5 compulsory, 5 to 9 optional