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Activity 2.1.3: Making Results Meaningful Introduction In the last activity, you saw how easy it is to manipulate and misinterpret data. When conducting scientific research, data analysis is essential to drawing meaningful conclusions from experimental results. In order to prevent data manipulation and misinterpretation, scientists use statistics (the collection, organization, and interpretation of numerical data) to objectively analyze experimental data. In this activity you will learn one process that scientists use to statistically analyze data. You will use this process to analyze the results of a scientific investigation. Equipment Computer with Internet access and presentation software Statistical Analysis presentation Statistical Analysis Resource Sheet Activity 2.1.3 Student Response Sheet Scientific calculator Laboratory journal Procedure 1. Take notes in your laboratory journal as your teacher presents the Statistical Analysis presentation. 2. Answer Conclusion questions 1 – 5. Refer back to your notes or to the Statistical Analysis presentation as needed. 3. Obtain pages 1 – 4 of the Statistical Analysis Resource Sheet from your teacher. 4. Obtain a Student Response Sheet from your teacher or from the mission file. 5. Follow all of the steps to statistically analyze the practice problem found on Part I: Example One of the Student Response Sheet. Make sure to show all work. You may use the Statistical Analysis Resource Sheet as well as the notes you took in your laboratory journal to help you. For all of your calculations, round your decimals to the nearest hundredths. 6. When you have completed all of the steps, show your work to your teacher and obtain the remainder of the Statistical Analysis Resource Sheet. 7. Compare your answers on Part I of your Student Response Sheet to the answers outlined in Example One on the Statistical Analysis Resource Sheet. Project Lead The Way, Inc. Copyright 2011 DRAFT – DO NOT COPY OR DISTRIBUTE BI – Activity 2.1.3 Making Results Meaningful – Page 1 8. Answer Conclusion question 6. 9. Read through the remainder of the examples on the Statistical Analysis Resource Sheet. 10. Note that your teacher will assign you and a partner one of the four studies found below. 11. Work with your partner to statistically analyze the results of your assigned study. Record your answers on Part II: Assigned Study of the Student Response Sheet. Make sure to show all of your calculations. 12. Have your teacher initial and date that you have successfully completed the statistical analysis on your Mission Completion Task list. 13. Make notes on the corresponding Notes section on your Mission Completion Task list. 14. Answer Conclusion question 7. Study One It is known that on average, adult males tend to have lower resting heart rates than females. A sports physiologist specializing in teenagers was interested in determining whether the same holds true for teenagers age 14 through 17. It was hypothesized that teenage males have lower resting heart rates than teenage females. To investigate this hypothesis, a researcher randomly selected 29 males and 29 females from PBS classes across the United States to determine whether the males enrolled in the class have lower resting heart rates than the females enrolled in the class. The participants’ heart rates were measured for two minutes while seated and resting and the average heart rate was calculated. The results of the experiment are listed in the following chart. Females Resting Heart Rate (bpm) 67 95 93 85 100 99 104 101 108 93 94 102 84 85 100 93 90 105 Males Resting Heart Rate (bpm) 90 74 83 94 72 87 86 84 70 69 92 84 84 97 100 96 90 74 Project Lead The Way, Inc. Copyright 2011 DRAFT – DO NOT COPY OR DISTRIBUTE BI – Activity 2.1.3 Making Results Meaningful – Page 2 99 91 101 104 107 107 98 107 109 83 100 83 94 72 90 74 83 94 72 87 86 84 Study Two A sports physiologist was interested in determining how short amounts of moderate exercise affect the heart rate of female teenagers. It was hypothesized that the average heart rate of teenage females after jogging for three minutes would be significantly higher than their resting heart rates. To investigate this hypothesis, a researcher randomly selected 21 females age 14 through 17 from PBS classes across the United States. The researcher compared their resting heart rates to their heart rates after jogging for three minutes. The participants’ resting heart rates were measured for two minutes while seated and resting and the average resting heart rate was calculated. The participants then jogged in placed for three minutes. Immediately after jogging, the participants’ heart rates were measured again for two minutes and the average heart rate after jogging was calculated. The results of the experiment are listed in the following chart. Average Resting Heart Rate (bpm) 100 75 96 98 103 84 93 116 87 97 93 86 76 97 72 72 72 70 Average Heart Rate After Jogging for 3 Minutes (bpm) 120 97 169 147 141 120 167 158 129 145 135 96 147 133 123 123 125 74 Project Lead The Way, Inc. Copyright 2011 DRAFT – DO NOT COPY OR DISTRIBUTE BI – Activity 2.1.3 Making Results Meaningful – Page 3 76 67 95 107 120 125 Study Three A sports physiologist was interested in determining how short amounts of moderate exercise affect the heart rate of male teenagers. It was hypothesized that the average heart rate of teenage males after jogging for three minutes would be significantly higher than their resting heart rates. To investigate this hypothesis, a researcher randomly selected 21 males age 14 through 17 from PBS classes across the United States. The researcher compared their resting heart rates to their heart rates after jogging for three minutes. The participants’ resting heart rates were measured for two minutes while seated and resting and the average resting heart rate was calculated. The participants then jogged in placed for three minutes. Immediately after jogging, the participants’ heart rates were measured again for two minutes and the average heart rate after jogging was calculated. The results of the experiment are listed in the following chart. Average Resting Heart Rate (bpm) 90 74 83 94 72 87 86 84 70 69 92 84 84 97 100 96 90 74 83 94 72 Average Heart Rate After Jogging for 3 Minutes (bpm) 136 120 142 149 125 99 138 184 160 78 103 128 110 148 118 121 136 120 142 149 125 Study Four A sports physiologist was interested in determining whether there is a difference in how short amounts of moderate exercise affect the heart rate of male teenagers versus female teenagers. It was hypothesized that the change in average heart rate of teenage males before and after jogging for three minutes would be lower than the change in Project Lead The Way, Inc. Copyright 2011 DRAFT – DO NOT COPY OR DISTRIBUTE BI – Activity 2.1.3 Making Results Meaningful – Page 4 average heart rate of teenage females before and after jogging for three minutes. To investigate this hypothesis, a researcher randomly selected 21 males and 21 females age 14 through 17 from PBS classes across the United States. The participants’ resting heart rates were measured for two minutes while seated and resting and the average resting heart rate was calculated. The participants then jogged in placed for three minutes. Immediately after jogging, the participants’ heart rates were measured again for two minutes and the average heart rate after jogging was calculated. The difference between the average heart rate before and after jogging was also calculated. The results of the experiment are listed in the following chart. Female Average Resting Heart Rate (bpm) 98 107 109 83 100 75 96 98 103 84 93 116 87 97 93 86 76 97 72 72 72 Female Average Heart Rate After Jogging in Place for 3 Minutes (bpm) 118 179 158 90 120 97 169 147 141 120 167 158 129 145 135 96 147 133 123 123 125 Change in Average Heart Rate (bpm) Male Average Resting Heart Rate (bpm) Male Average Heart Rate After Jogging in Place for 3 Minutes (bpm) Change in Average Heart Rate (bpm) 20 72 49 7 20 22 73 49 38 36 74 42 42 48 42 10 71 36 51 51 53 90 74 83 94 72 87 86 84 70 69 92 84 84 97 100 96 90 74 83 94 72 136 120 142 149 125 99 138 184 160 78 103 128 110 148 118 121 136 120 142 149 125 46 46 59 55 53 12 52 100 90 9 11 44 26 51 18 25 46 46 59 55 53 Conclusion 1. What is the purpose of statistically analyzing study data? To determine within a set of statistical parameters whether events validate or invalidate the null hypothesis. Project Lead The Way, Inc. Copyright 2011 DRAFT – DO NOT COPY OR DISTRIBUTE BI – Activity 2.1.3 Making Results Meaningful – Page 5 2. Why should you calculate the mean and standard deviation for sample data? Mean determine the idea of central tendencies and the deviation determines the degree of variability in the data around the mean. This tells you a considerable amount about the population in question. 3. What is the purpose of using a t-test when analyzing study data? The purpose of using a t-test is to determine if there is a statistical difference between the two populations in question. 4. How do you decide which type of t-test is the most appropriate for the study data you want to analyze? If the populations are the same individuals (paired) or are matched (paired t-test weight loss over time) compared to more independent groups where you are comparing the means (student t-test – dogs fed on different chow). 5. What does it mean if the t-test shows that the results are not statistically significant? If something is not statistically significant we accept the alternative hypothesis – that there is not difference between the two or more groups tested. 6. What does it mean that the results are not statistically significant for this study? If there is no significant difference, which indicates that there is no statistical difference in the measured variables of heart rate between males and females. 7. What do the results of this study mean? In study number one the analysis (one-tailed t-test) indicates that there is a statistical difference (p=less than 0.05) indicating males resting heart rates are slower than female heart rates. For problem three the data analysis (paired-ttest) indicates that that heart rates are significant difference after a period of exercise (p=less than 0.05) indicating that after exercise heart rate has increased. Project Lead The Way, Inc. Copyright 2011 DRAFT – DO NOT COPY OR DISTRIBUTE BI – Activity 2.1.3 Making Results Meaningful – Page 6