Back to the Kiwis…

1. Back to the Kiwis…

2. Kiwi Kapers 2 The impact of sample size…

3. Problem • I wonder what the median weight of New Zealand kiwis is?

4. Using technology… Remember we’re in TEACHING WORLD - in the ‘real world’ we wouldn’t be able to take lots and lots of samples to see what happens! • Sampling kiwis • Collecting the medians from repeated sampling

5. Your collection of medians...

6. Analysis • For each sample size: • I notice that the sample median weights of kiwis for samples of size ___vary from ___ to ___ • I notice that the bulk of the sample median weights of kiwis for samples of size ___ranged from ___ to ___ • I notice that the median for the sample median weight of kiwis for samples of size ___ is ___ and that the median for the sample IQR is ___

7. Analysis

8. Analysis • I notice that the variation of the median weights of kiwis ________ as the sample size _________. • For samples of size 15 the median weight ranged from ____ to ____, a difference of _____, • Whereas for samples of size 100 the median weight ranged from ____ to ____, a difference of ____.

9. Question? • What do you think will happen to variation in the IQR of the samples as we increase the sample size? • 12kiwipopsample2IQR

10. Conclusion As the sample size increases, the variation of the medians __________ the variation of the IQRs _____________ • What is a sensible and reliable sample size to use to make inferences about the population?

11. Conclusion Remember • Our best point estimate of the population parameter – the population median is our sample median • The estimates vary, even with n = 100 • It is better to provide a range of possible values for the parameter, based on our estimate, rather than stating one value

12. Developing a reflex… ..\..\..\Pip\Animations_WILD\boxes_1samp_mem_30.pdf

13. We want to plant a reflex…

14. Movies – one sample - summary Box plot with memory…