Problem set 1 solutions (ABC)

Problem set 1 solutions (ABC) - Problem set 1 solutions A:...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Problem set 1 solutions A: t-test practice 1. (a) H : x 30 H A : x <30 (b) 1-tailed 1-sample t-test (c) t = -0.4657, df = 12, P = 0.3249 (d) At all levels of alpha, p> so we fail to reject the null hypothesis and conclude that this species does not maintain a coelomic calcium concentration less than that of their environment. 2. (a) H : x =24.3 H A : x 24.3 (b) 2-tailed, 1-sample t-test (c) t = 2.7128, df = 24, P = 0.01215 (d) For = 0.1 and 0.05, p< so we reject the null hypothesis and conclude that the crabs maintain a body temperature different than air. For = 0.01 and 0.001, p> so we fail to reject the null hypothesis and conclude that the crabs maintain a body temperature the same as the air. 3. (a) H : x =29.5 H A : x 29.5 (b) 2-tailed, 1-sample t-test (c) t = -2.2859, df = 13, P = 0.03968 (d) For =0.1 and 0.05, p< so we reject the null hypothesis and conclude that average human menstrual cycle does not equal a lunar month. For =0.01 and 0.001, p> so we fail to reject the null hypothesis and conclude that the average human menstrual cycle equals a lunar month. 4. (a) H : x 45 H A : x > 45 (b)1-tailed, 1-sample t-test (c) t = 0.3665, df = 7, P = 0.3624 (d) For =0.1, 0.05, 0.01, and 0.001, p> so we fail to reject the null hypothesis and conclude that the mean dissolving time is less than or equal to 45 seconds. 5. (a) H : x 45 H A : x < 45 (b) 1-tailed, 1-sample t-test (c) t = 0.3665, df = 7, P = 0.6376 (d) For =0.1, 0.05, 0.01, and 0.001, p> so we fail to reject the null hypothesis and conclude that the mean dissolving time greater than or equal to 45 seconds. [Combining questions 4 and 5, if we use a 2-tailed, 1-sample t-test with H : x =45 and H A : x 45, (t = 0.3665, df = 7, P = 0.7248). p> so we fail to reject the null hypothesis and conclude that the mean dissolving time is 45 seconds.] 6. (a) H : = G H A : G (b) Welch 2-tailed, two-sample t-test (c) t = -2.54, df = 10.7, P = 0.0277 (d) For =0.1 and 0.05, p< so we reject the null hypothesis and conclude that the drugs differ in their effectiveness (mean blood-clotting times are not the same). For =0.01 and 0.001, p> so we fail to reject the null hypothesis and conclude that there is no difference in the mean effectiveness of the drugs (the mean blood-clotting times are the same). Note that if we had assumed equal variances then P=0.031, which doesnt change our conclusions. The variances differ by a factor of two, which is relatively large, but because of the small sample size we cant reject the null hypothesis that they are the same (use Statistics -> Variances -> Two variances F-test). Nonetheless, the Welch test makes fewer assumptions, so is preferable....
View Full Document

This note was uploaded on 08/06/2008 for the course ESM 206 taught by Professor Kendall,berkley during the Spring '08 term at UCSB.

Page1 / 12

Problem set 1 solutions (ABC) - Problem set 1 solutions A:...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online