If the means of the two sets are very different then

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see if they’re the same or different. If the means of the two sets are very different, then it’s easy to tell. But, often the means are quite close and it is difficult to judge whether the two sets are significantly different. The t-test compares the actual difference between two means in relation to the variation in the data (expressed as the standard deviation of the difference between the means). In other words, the t test compares two sets of data and tells you the probability (P) that the two sets are basically the same. E X E R C I S E I : Y A Y O R N A Y ? Write down your question again in your lab notebook. 1. Write down your question again in your lab notebook. 2. Did your data and data analysis support this question? If your answer was Yes, please explain what data supports your question. If your answer was No, explain what data does not support your question. 3. If your answer was No, you need to re-design your question. Or perhaps you need to increase your sample size. Let’s look at the class data as a whole. How do you think this will change the data analysis? Is sample size important?
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Science Research Mentoring Program STATISTICS © 2013 American Museum of Natural History. All Rights Reserved. 33 WORKSHEET: T-tests & Chi Square (continued) E X E R C I S E I I : S A M P L E S I Z E A N D A C C U R A C Y ? A C C U R A C Y & P R E C I S I O N Accuracy is how close a measured value is to the ________________ value. Precision is how close the measured values are to ________________________. High Accuracy Low Precision High Accuracy Low Precision High Accuracy High Precision So, if you are playing soccer and you always hit the left goal post instead of scoring, then you are not _____________________, but you are _______________________!
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Science Research Mentoring Program STATISTICS © 2013 American Museum of Natural History. All Rights Reserved. 34 Session Six: Support or Rejection of Hypothesis: ACTIVITY Accuracy & Precision P R O C E D U R E Collect the length and width data from each of the other groups. Record the data in your lab notebooks. 1. Our groups sample size was: 2. The class sample size was: 3. What is the range of length and width for your data? Length: Width: 4. What is the range of length and width for the class data? Length: Width: 5. Is there a difference in these measurements? 6. What was the class average for length _______ and width _______. 7. What was your averages for length ______ and width ______. 8. How does your average compare to the class average? 9. Do you feel confident with your sample size? What could have been done to achieve greater confidence?
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  • Fall '17
  • Statistics, Natural history, American Museum of Natural History, American Museum, Science Research

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