Psych Statistics - Midterm Exam Questions With Multiple Choices And Answers.

Frequency table is better than histogram in summarizing data when ____. - correct answers the data come from a nominal variable On the first exam in an introductory statistics class, the vast majority of students did very well and scored between 80% and 100%, with only a small number of students performing poorly, with scores lower then 60%. What is the description that fits the distribution best? - correct answers The distribution is left-skewed. Which of the following is an example of a continuous (equal-interval) variable? - correct answers Monthly salary amount In a perfectly symmetrical unimodal distribution, _____. - correct answers the mode is the same as the mean Jake's Z score on an IQ test is -0.8. What is Jake's raw score (assuming M =100 and SD = 15)? - correct answers88 To gather feedback on a new iPhone app, users are asked to rate the app on a scale of 1 to 5 in terms of "ease of use", with 1 being very difficult to use and 5 being very easy to use. The feedback data from this single question would be considered a(n) ____ variable. - correct answersordinal What is the probability of drawing a score from a normal distribution of scores that can be converted into a Z score between +1.5 and -1.5? (Use the Z table) - correct answersa. .8664 c..4332 d. .1336 Japan has been said to have a longer life expectancy compared to that of the US. A research study was conducted to examine that informal observation. Life expectancy data were collected from 5000 Japanese people who passed away due to natural causes in the past 12 months to compare with the US national statistics. What are the sample and the population on which the inference would be made? - correct answersThe 5000 Japanese; Population: All Japanese people What is the best sample for inferential statistics? - correct answersA sample randomly selected from the population of interest. A hypothesis test result is considered statistically significant when a sample statistic is so extreme that ____. - correct answersa. the probability of the null hypothesis being true is lower than the alpha level c. the probability of the research hypothesis being false is lower than the alpha level d. the probability of the null hypothesis being false is lower than the alpha level For a given sample statistic and a fixed alpha level, how does a one-tailed test compared to a two-tiled test? - correct answersThe critical value to be compared to the statistic would be more extreme with a two-tailed test. If you draw a normal distribution and mark the left tail end for 5% of the total area in the curve, what would be the Z score that serves as the border of that tail region? - correct answers-1.65 A research agency recently published the national statistics on college students' usage of social network apps on their mobile devices. If I collect some data from my students in the ASU online program to see if ASU online students differ from the national statistics in social network usage, what would be my non-directional null hypothesis for a two-tailed hypothesis test? - correct answersASU online students do not differ significantly from the national college population on social network usage. A researcher reports a study where he compared the cognitive functions of a small group of elderly adults who used iPads regularly to the national norms of cognitive function in the elderly age group. Although the hypothesis test result was not significant, the effect size was of medium size. What is the appropriate interpretation of the finding of the study? - correct answersFuture replication of the study with a larger sample would be informative on the topic. The sampling distribution consists of _____. - correct answersa. all the means of potential samples drawn from the original population b. all the scores in the original population where the sample is drawn c. all the difference scores A market researcher wants to know if Toyota vehicles have significantly higher MPGs compared to the national statistics. She sets the α (significance) level at .05 for a one-tailed test. The Z statistic calculated from the Toyota sample is 1.83. What is the conclusion from this hypothesis test? - correct answersThe null hypothesis is rejected and Toyota vehicles have significantly higher MPGs compared to the national data. The Z statistic for a hypothesis test is -2. The comparison population has a mean of 50 and the standard error is 7. What would be the mean of the sample? - correct answers36 Compared to a sampling distribution with a mean of 100 and a standard error of 10, what is the Z statistic for the sample that consists of 98, 102, 108, 104. - correct answers0.3 Z tests are rarely seen in published studies because ____. - correct answersThe comparison population mean and standard deviation are rarely available to the researcher Increasing statistical power of a study would ____. - correct answersincrease the probability of rejecting the null hypothesis when it is actually false The sample consists of the scores, 3, 3, 5, 5, 7, 7. What is the standard deviation? - correct answers1.63 Roughly speaking, the concept of _____ is a measure of the average distance between the scores and the mean. - correct answersstandard deviation When calculating the variance of a group of numbers, the difference between each data point and the mean needs to be squared. What is the rationale behind this step? - correct answersa. To make sure all the numbers are positive and won't cancel each other out when the differences are added up. c. To make the differences between the data points and the mean larger and easier to handle. d. The difference between each data point and the mean is the standard deviation. What is the standard deviation of the sample that consists of 3, 4, 6, 7, 10? - correct answers2.45 In the graduating class of the local high school, 20% of the students have decided to attend Arizona State University. If I randomly draw a student from the graduating class, what is the probability that the chosen student will be attending ASU? - correct answers0.20 A researcher conducts hypothesis testing on the the effect of an encoding strategy on memory performance. The null hypothesis states that the encoding strategy has no effect on memory performance while the alternative hypothesis states that the encoding strategy has an effect on memory performance. A "significant" test result means that _____. - correct answersthe probability is low enough for the null hypothesis so it can be rejected What minimum Z score does a student need to get to be ranked in the top 1% of her/his class? (Use the Z table) - correct answersaround 2.33 When using the Z table for a two-tailed hypothesis test with a preset alpha (significance) level, what is the correct sequence of the following steps: A. Look for the corresponding Z value(s) B. Convert the alpha to percentage C. Look in the "tail" column for the "tail area percentage" D. Divide the percentage from alpha by 2 to be the "tail area percentage" - correct answersB-D-C-A I conducted a study on the effect of Parkinson's disease on memory by comparing a group of Parkinson's patients to the general population in the same age range. Based on the statistical result, I failed to reject the null hypothesis so I can conclude that ____. - correct answersthe probability is high that the memory abilities of Parkinson's patients are no different from the general population (Mpopulation 1 − Mpopulation 2) is a formula for figuring ____. - correct answersraw effect size A cognitive psychologist created a brain training program to help children with ADHD to focus better. She wants to recruit a sample of children with ADHD for the training program and then conduct a two-tailed test comparing the sample's attention span with the general population of children with ADHD. What is the non-directional alternative hypothesis for her study? - correct answersThe attention span differs between ADHD children who have gone through the brain training program and those who have not gone through the brain training program. A teacher conducted a study to see if the students in his school performed significantly worse than the national average on a standardized math test. He calculated the Z statistic to be -2 while the critical value for the hypothesis test was -1.96. He would conclude that ___. - correct answersb. the null hypothesis was rejected and the students in his school performed significantly worse than the national average. c. the null hypothesis could not be rejected and the students in his school performed significantly worse than the national average. d. the null hypothesis could not be rejected and the students in his school did not perform significantly worse than the national average. Why do researchers perform a power analysis before conducting a study? - correct answersTo determine the number of participants required for the study. In a research article, the hypothesis test result was not significant and the researcher reported the statistical power of the study to be relatively low. The logical interpretation of the data analysis would be that ____. - correct answersthe test result was inconclusive A new variety of apples has been developed to be bigger than the typical apples, which average 7 oz in weight. The critical Z value for a hypothesis test is 1.96 and the standard error is 2 oz. What is the minimum weight (in oz) of the sample of new apples to yield a significant test result? - correct answers10.92+