Fundamentals of Inferential Statistics — DU B.A (Prog.) Psychology as Major Previous Year Question Papers

Attempt questions from all Sections. Statistical tables will be provided. 1. (a) - What are the two types of hypotheses in statistical inference ? Using a suitable example, differentiate between one-tailed and two-tailed tests. (b) A psychologist claims that the average anxiety score in a population is 50. A sample of 20 students produced a mean score of 54. The estimate of the standard deviation' of the population (sp) was found to be 8. Calculate t"and test whether the sample mean is significantly higher than the population mean. Use a = 0:05. (one tailed test). 5 (c) A researcher wants to'see if a 15-minute meditation affects stress levels in 4 students : - " .. 10 Student Before Meditation After Meditation Test whether meditation reduces stress scores. Evaluate t-test (two-tailed) at a = 0.01. 2. (ai) Describe the assumptions associated with t-test for independent samples. Explain the impact of violation of these assumptions. 5 (b) A researcher wants to compare problem-solving performance between students who received interactive learning and those who received traditional learning. The following scores were obtained : 15 Interactive Learning Group : 7, 6, 8, 5, 7 Traditional Learning Group: 4, 5, 6, 3, 4 Set up Ho and Ha (non-directional), evaluate t at a = 0.05 and draw final conclusions. - 3. (a) What are confidence intervals ? Discuss the merits of confidence intervals over hypothesis testing. 5 Construct a confidence interval of Ix according to C = 0.99. 5 (c) GivenX=25, Y=28, sx=13, sy =10, n= 16,, 'xx = +0.62. Assuming samples to be dependent, construct a, 95% confidence, interval of 4. (a) What is ANOVA? Why does the region of rejection in the F' test lie only in the upper tail of the distribution ? 5 (b) A researcher wants to compare the effect of three different diets on weight loss (in kg) after one month. Scores for 3 participants in each diet group are : 15 Diet A • Diet B Diet C Express Ho and HA. Calculate the F-ratio to test whether there is a significant difference in weight loss among diets at a = '0.01. Diet A Diet B Diet C (a) What' is the Chi-square test ? Examine its characteristics. 5 (b) A school wants to examine whether gender is associated with preference for co-curricular activities among students. A sample of 100 students was surveyed; and the following results were obtained : 15 Activity Sports Music Art Test the null hypothesis of independence using the X? test (a = 0.05) and state your conclusions. 6. (a) Describe the two types of errors in hypothesis testing. 5 (b) If you set a stringent alpha level (say 0.001), what is the effect, on the probability of Type I error and Type II errors? 7. (a) Using suitable examples, describe the independent: and dependent samples design. 5 (6) A repeated-measures t test reports a p value of p'= 0.021. Can the résearcher claim a significant effect with a = 0.01? Explain. 5 8. (a) Is it possible to retain Ho at a = 0.05 but reject it at a = 0.01? Illustrate with a figure. 5