Statistics for the Behavioral Sciences, Sixth Edition by Frederick J. Gravetter and Larry B. Wallnau Copyright © 2004 by Wadsworth Publishing, a division of Thomson Learning. All rights reserved. Figure 12-1 (p. 371) The basic research situation for either hypothesis testing or estimation. The goal is to use the sample data to answer questions about the unknown population mean after treatment.

Statistics for the Behavioral Sciences, Sixth Edition by Frederick J. Gravetter and Larry B. Wallnau Copyright © 2004 by Wadsworth Publishing, a division of Thomson Learning. All rights reserved. Figure 12-2 (p. 373) For estimation or hypothesis testing, the distribution of t statistics is divided into two sections: the middle of the distribution, consisting of high-probability outcomes that are considered “reasonable” and the extreme tails of the distribution, consisting of low-probability, “unreasonable” outcomes.

Statistics for the Behavioral Sciences, Sixth Edition by Frederick J. Gravetter and Larry B. Wallnau Copyright © 2004 by Wadsworth Publishing, a division of Thomson Learning. All rights reserved. Figure 12-3 (p. 376) The structure of the research study described in Example The goal is to use the sample to estimate the population mean for students with the special summer program. We can then estimate how much effect the special program has on students’ reading scores.

Statistics for the Behavioral Sciences, Sixth Edition by Frederick J. Gravetter and Larry B. Wallnau Copyright © 2004 by Wadsworth Publishing, a division of Thomson Learning. All rights reserved. Figure 12-4 (p. 377) The 80% confidence interval with df = 24 is constructed using t values of t = –1.318 and t = The t values are obtained from the table using 20% (0.20) as the proportion remaining in the two tails of the distribution.

Statistics for the Behavioral Sciences, Sixth Edition by Frederick J. Gravetter and Larry B. Wallnau Copyright © 2004 by Wadsworth Publishing, a division of Thomson Learning. All rights reserved. Figure 12-5 (p. 378) A representation of the estimates made in Example Before a special summer reading program, the population mean reading score was  = 81. Based on a sample, the special program is estimated to increase the mean to  = 88 (point estimate), or somewhere between and (interval estimate).

Statistics for the Behavioral Sciences, Sixth Edition by Frederick J. Gravetter and Larry B. Wallnau Copyright © 2004 by Wadsworth Publishing, a division of Thomson Learning. All rights reserved. Figure 12-6 (p. 380) The distribution of t values with df = 13. Note that t values pile up around zero and that 95% of the values are located between –2.160 and

Statistics for the Behavioral Sciences, Sixth Edition by Frederick J. Gravetter and Larry B. Wallnau Copyright © 2004 by Wadsworth Publishing, a division of Thomson Learning. All rights reserved. Figure 12-7 (p. 382) The t values for the 90% confidence interval are obtained by consulting the t tables for df = 15, p = 0.10 for two tails.

Statistics for the Behavioral Sciences, Sixth Edition by Frederick J. Gravetter and Larry B. Wallnau Copyright © 2004 by Wadsworth Publishing, a division of Thomson Learning. All rights reserved. Figure 12-8 (p. 384) The 95% confidence interval for the population mean difference (  1 –  2 ) from Example Note that  1 –  2 = 0 is excluded from the confidence interval, indicating that a zero difference is not an acceptable value (H 0 would be rejected in a hypothesis test).