Recap…  We need to take spread into account when we give an interval for the population parameter

So far… Population Sample Sample statistics Population parameter What we’re trying to estimate

Remember our kiwis…

So far… Population Sample Sample statistics What is the median weights of kiwis? What we’re trying to estimate Take your sample of kiwis Dot plot Box plot Sample statistics…

So far… Population Sample Sample statistics Population parameter What we’re trying to estimate Median weight of kiwis is somewhere between ___ and ___

Samples of size ___ were reliable enough

The median weight of kiwis was somewhere between ___ and ___ (90% ish of our sample medians) Distribution of sample medians…

We don’t get to take multiple samples so this process WON’T work We need to find an informal confidence interval for the population median based ON A SINGLE SAMPLE However in real life …

To take into account both Sample size and spread Our informal interval needs…

For your sample of kiwis: Dot plot Box plot Median More kiwis…

Add your SAMPLE MEDIANS TO THE SHEET Then

Add your IQR (box) TO THE SHEET Student worksheet

Complete Q3 – Q5 on the worksheet Student worksheet

Q3: I notice that the width of the IQR for sample medians when the sample size is 30 is approximately of the width of the population IQR WIDTH kg-ish (67 mm) WIDTH kg-ish (11 mm) 1/5

Q4: I notice that the width of the IQR for sample medians when the sample size is 400 is approximately __________ of the width of the population IQR WIDTH kg-ish (3.5 mm) WIDTH kg-ish (67 mm) 1/20

Q5: Relationship between the width of the IQR for sample medians of sample size n and the population IR and the sample size…  IQR for sample medians (sample size = n) is approximately of the population IQR  When n = 400 the IQR of the sample medians is approximately ________________ of population IQR  When n = 30 the IQR of the sample medians is approximately ________________ of population IQR