Pracice: Hand Calculaion of -es for Independen Means(Temperaure & Mood) Auhor(s) Naalie Ciarocco Insiuion Monmouh Universiy Tile of Resource This aciviy can be used as pracice afer sudens have learned how o hand calculae a -es for independen means. Keywords: -es for Independen Means; Hand Calculaion Brief Descripion: Auhor Conac Informaion: Addiional Informaion: nciarocc@monmouh.edu TeachPsychScience.org is made possible wih gran suppor from he Associaion for Psychological Science (APS) Fund for Teaching and Public Undersanding of Psychological Science o he sie creaors Gary Lewandowski, Naalie Ciarocco, and David Srohmez. All maerials on his sie have been subjeced o a peer review process. We welcome addiional resources (www.eachpsychscience.org/submissions). 010 by Naalie J. Ciarocco. All Righs Reserved. This maerial may be used for noncommercial educaional purposes. All oher uses require he wrien consen of he auhors.
Insrucors: Insrucors should assign his problem o sudens as in-class pracice or homework afer sudens have learned how o calculae a -es for independen means and es for significance. The aciviy leads sudens hrough deermining he ype of saisical analysis o use, he hypoheses, calculaing he -raio and effec size (if appropriae), making a decision abou he null hypohesis and summarizing he resuls. An answer key is included.
Pracice: -es Two groups were randomly assigned o spend 15 minues eiher in a ho room (defined as 90 degrees) or a cold room (defined as 30 degrees). Afer he 15 minues elapsed, a mood measure was compleed by paricipans. Scores on he measure of mood ranged from 1-0, wih higher scores indicaing a beer mood. Using an alpha of.05, es for a difference beween he groups. Group 1 (ho) Group (cold) 13 8 1 8 1 5 9 3 8 3 8 1. Which ype of es will you use?. Sae H 0 and H 1. 3. Is his a one-ailed or wo ailed es? Why? 4. Wha are he degrees of freedom associaed wih his es? 5. Wha is/are he criical value(s) one should use o es he researcher s hypohesis? 6. Calculae he -raio. Be sure o show all of your work. 7. Wha is your decision regarding he null hypohesis? Explain 8. Calculae he effec size (if applicable). Explain wha he effec size ells us. 9. Give a summary saemen abou he resuls. Think abou he decision regarding he null, he group means and effec size (when applicable).
ANSWERS Pracice: -es Two groups were randomly assigned o spend 15 minues eiher in a ho room (defined as 90 degrees) or a cold room (defined as 30 degrees). Afer he 15 minues elapsed, a mood measure was compleed by paricipans. Scores on he measure of mood ranged from 1-0, wih higher scores indicaing a beer mood. Using an alpha of.05, es for a difference beween he groups. Group 1 (ho) Group (cold) 13 8 1 8 1 5 9 3 8 3 8 1. Which ype of es will you use? Independen samples -es is he appropriae analysis as he wo groups of paricipans are no relaed in any way.. Sae H 0 and H 1. Null: There is no difference in mood beween people in a ho room and a cold room. Alernaive: There is a difference in mood beween people in a ho room and a cold room. 3. Is his a one-ailed or wo ailed es? Why? The alernaive hypohesis is non-direcional, herefore he es is wo-ailed. 4. Wha are he degrees of freedom associaed wih his es? df n 1 n df 6 + 6 10 5. Wha is/are he criical value(s) one should use o es he researcher s hypohesis? The criical value of.8 6. Calculae he -raio. Be sure o show all of your work. X 1 X 1 - M (X 1 M) X X - M (X M) 13 13-10.33 6.67 7.13 8 8-4.83 3.17 10.05 1 1-10.33 1.67.79 8 8-4.83 3.17 10.05 1 1-10.33 1.67.79 5 5-4.83.17.03 9 9-10.33-1.33 1.77 3 3-4.83-1.83 3.35 8 8-10.33 -.33 5.43 3 3-4.83-1.83 3.35 8 8-10.33 -.33 5.43-4.83 -.83 8.01 X 1 6 (X 1 M) 5.34 X 9 (X M) 34.84 N 1 6 N 6 M 1 10.33 M 4.83
S ( Χ Μ ) + ( Χ Μ ) 1 1 n + n 1 5.34 + 34.84 S 60.18 S S 6. 0 6 + 6 10 Μ 1 Μ 1 1 + S n1 n 10.33 4.83 1 1 + 6.0 6 6 5.5.01 5.5 1.4 3. 87 7. Wha is your decision regarding he null hypohesis? Explain The null hypohesis should eb rejeced as he -raio calculaed is greaer han criical value. 8. Calculae he effec size (if applicable). Explain wha he effec size ells us. r effec size + df r effec size 3.87 3.87 + 10 14.98 reffec size r size. 5997 4.98 effec r effec size.77 This is a srong effec size, herefore he finding is imporan. 9. Give a summary saemen abou he resuls. Think abou he decision regarding he null, he group means and effec size (when applicable). There is a difference in mood when one is in a ho room versus a cold room. This is an imporan difference. People are in a beer mood when in a ho room (M 10.33) hen when in a cold room (M 4.83).