Data Collection, Statistical Analysis, Cell Size vs. Diffusion The calculation of t is: |x-X| t= C C (n + n-2) B-2))(+) t(calc) = 70.9-70.4 | 9 (1419.4/20) (1/11 + 1/11) Calculating t by hand gives t = 0.136, by computer gives t = 0.139 for this data. In science, if the t value has a probability of 0.05 or less we say it is significant. This says the probability of getting this much difference or more by chance alone from two different data sets is less than 5%. The table in Appendix B has t values significant at various degrees of freedom. First, calculate degrees of freedom (df) for your data: df = n1 - 1 or n2 - 1 which ever is smaller. df for heart rate data = Note that the degrees of freedom value (df) is required to use the t table in Appendix B. t value in the table (corresponds to df) for heart rate data = If the calculated t value is greater than the t value in the table which corresponds to your degrees of freedom, then there is a significant difference. If your t value is less than or equal to the t value in the table that corresponds to your degrees of freedom, then there is no significant difference between the two groups. Is there a significant difference between these two groups? Another treatment of data that frequently is helpful in seeing relationships among the events that were recorded is to calculate the percentage that each value represents. In general, the equation for calculation percentages is: % (individual value) X 100 = (sum of the values) Degrees of Freedom n-1 = 3 2-5 Data Collection, Statistical Analysis, Cell Size vs. Diffusion Table 2.1: Class Data Student # X= Male X2 X= Female X Height (cm) Height (cm) 1 162.5 26406.25 152.4 23225.76 2 172.72 29832-2 160.02 25606.40 3 172.72 29832.2 177.8 31612.84 4 164.9 27192.01 160.02 25606.40 5 180.3 3.2508.09 152.4 23225.76 6 162.6 26438.76 7 167.6 28089.76 8 160.02 25606.40 9 165.1 27258.01 10 165.1 27258.01 11 167.6 28089.76 12 160.02 25606.40 13 157.48 24799.95 14 167.64 28103.1 15 167.64 28103.1 16 157.48 24799.95 17 154.48 24006.40 18 164.6 27093.16 19 20 21 22 23 24 Total Average 853.14 170.628 145,770.74 2920.46 331,790.76 162.247 std dev. Data Collection, Statistical Analysis, Cell Size vs. Diffusion Statistical Analysis of Male versus Female body height Perform a t-test to determine whether or not there is a significant difference between male versus female height. Calculate the values shown in the table below. (Show ALL calculations here.) Table 2.2 VALUE Male Female t calculated: n A 5 853.14 170.628 18 2920.46 B 145,770 C 162.247 331,790.76 df: t-table (Appendix B) Questions: 1. Is there a significant difference between the two groups? Explain. Which hypothesis was correct?