LAB 2
PROBLEM STATEMENT 1 It is known that a certain laboratory task takes the average person 2.5 seconds. A developmental psychologist was interested in whether older people take longer to perform this task. The psychologist tested 30 randomly selected 80-year-olds. Their mean time was 2.7 seconds, with an estimated population standard deviation of 1.4 seconds. What should the psychologist conclude (use the .05 level)? 1. Restate the question as a research hypothesis and a null hypothesis about the populations. (2 points) 2. Determine the characteristics of the comparison distribution: Population mean = (1 point) Population variance = (1 point) Standard deviation of the distribution of sample means = (1 point) Degrees of Freedom = (1 point) 3. Determine the significance cutoff. Use the t table. (1 points) 4. Determine your sample’s score on the comparison distribution. (2 points) 5. Decide whether to reject the null hypothesis. (2 points) Set Up Hypothesis Null Hypothesis H0: U = 2.5 Alternate, mean response time of older people slower than the response time of people in general H1: U>2.5 Test Statistic Population Mean(U)=2.5 Given That X(Mean)=2.7 Standard Deviation(S.D)=1.4 Number (n)=30 we use Test Statistic (Z) = x-U/(s.d/Sqrt(n)) Zo=2.7-2.5/(1.4/Sqrt(30) Zo =0.7825 | Zo | =0.7825 Critical Value The Value of |Z ?| at LOS 0.05% is 1.64 We got |Zo| =0.7825 & | Z ? | =1.64 Make Decision Hence Value of |Zo | < | Z ? | and Here we Do not Reject Ho P-Value : Right Tail - Ha : ( P > 0.7825 ) = 0.217 Hence Value of P0.05 < 0.217, Here We Do not Reject Ho accept hypothesis, we don't have evidence that mean response time of older people slower than the response time of people in general