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We love our kiwis…. Introduction…. CLAIM Brenna says that female kiwis are taller than male kiwis. Problem. CLAIM Brenna says that female kiwis are taller than male kiwis. We will look at the height of kiwis to investigate this claim. Investigative question
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Introduction… CLAIM Brenna says that female kiwis are taller than male kiwis.
Problem CLAIM • Brenna says that female kiwis are taller than male kiwis. • We will look at the height of kiwis to investigate this claim. Investigative question • I wonder if the median height of NZ kiwi females tends to be greater than the median height of NZ kiwi males?
Investigative question Population parameter • I wonder if the median height of NZ kiwi females tends to be greater than the median height of NZ kiwi males Variable of interest Groups/sub-populations Population
Plan • We will use a simple random sample of 30 female kiwis and 30 male kiwis from the database of NZ kiwis on Census@Schools • Why have we chosen 30 of each gender? • From our SRS, we will calculate an informal confidence interval for the population median for female heights and an informal confidence interval for the population median for the male kiwi heights.
Plan That is – we’ll calculate TWO informal confidence intervals • Females • Males
Data • I sampled for you • Have a look how… • http://www.censusatschool.org.nz
AnalysisSelect and use appropriate displays and measures.Construct the informal confidence intervals
AnalysisDiscuss sample distributions by comparing features of them. Compare - shape - overlap - shift - spread- middle 50%- unusual or interesting
Conclusion - inference • From my informal confidence intervals, I am pretty sure that the population median height of NZ kiwi females is between ____ and ____. • Similarly, I’m pretty sure that the population median height of NZ kiwi males is between ____ and ____.
Conclusion • Based on these samples I would make the call that the population median height of NZ kiwi females is greater then the population median height of NZ kiwi males. That is, I would make the call that NZ kiwi females tend to be taller than NZ kiwi males back in the two populations.
Conclusion - justification • The informal confidence interval for the population median height of NZ kiwi females is (much) further up the scale than the informal confidence interval for the population median height of NZ kiwi males and these informal confidence intervals do not overlap. • I am quite sure that if I were to take another sample of NZ kiwi females and another sample of NZ kiwi males girls this non-overlapping pattern in confidence intervals for the population medians would persist, thus giving the same conclusion.
Conclusion Further thoughts… • What would happen if you took another sample and completed this process again? • What would happen if to the informal confidence intervals if you increased the sample size?
