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Chapter 11 - Analyzing and Interpreting
Data
When studying an island population of scrub jays, a researcher suspects that the individuals she is observing are uniquely different in their overall size from the mainland population. What is the appropriate method to determine if the researcher's suspicions are accurate? - correct answer ✔✔using inferential statistics to compare the populations Which of these cannot be provided by descriptive statistics? - correct answer ✔✔evaluate a hypothesis about the population When analyzing a sample from a population, the characteristics of the sample are referred to as the _____. - correct answer ✔✔statistics A researcher has exhaustively measured every individual from a population and arrived at 0.5 grams as the mean size for an individual. In calculating this mean, the researcher has provided us with what characterization of the population? - correct answer ✔✔parameter Which of these is not considered a descriptive statistic? - correct answer ✔✔t test Which of these levels of measurement requires a meaningful zero point? - correct answer ✔✔ratio A marketing firm has been hired by a cola company to review how their cola drink compares to their two major competitors. The marketing firm conducts a series of comparison trials at the grocery stores and public areas around the region where volunteers are asked to rank the cola drinks on three criteria from most to least favorable. What type of data is being collected by this research? - correct answer ✔✔ordinal Which of these instruments measure on an interval scale? - correct answer ✔✔thermometer
Which of these levels of measurement address categorical data? - correct answer ✔✔nominal Which of these is an indicator that data is at least on an interval scale? - correct answer ✔✔equal spacing between values A soccer coach is conducting trials for an open position but too many people have arrived to try out. As a strategy, the coach has divided the tryouts into a set of basic skill tests. By only keeping the top half of performers from every skill trial, she is able to weed out poor candidates. What form of central tendency must she use to decide who can stay and who should leave? - correct answer ✔✔median As required by the school district, each school nurse must conduct an annual review of the students' health. Height and weight peak at a different value for boys and girls. Upon calculating the descriptive statistics for each grade level, the nurse realizes that a mean is the wrong measure of central tendency for a grade level. Why would this be the case? - correct answer ✔✔The sample shows a bimodal distribution. The mean is the most widely used statistic for describing central tendency. However, the mean can be heavily influenced by _______. - correct answer ✔✔outliers A coffee buyer makes regular visits to the coffee-growing regions of the world to collect samples for testing. Because of the nature of bean collection, a sample often has many beans on the larger end of the size range with fewer beans at a lower size. Which is the appropriate descriptive statistic to use if the coffee buyer wished to describe the most common bean size for the sample? - correct answer ✔✔mode Which measure of central tendency can be used to summarize all levels of measurement (nominal, ordinal, interval, and ratio)? - correct answer ✔✔mode Which of these measures of dispersion is calculated by taking the square root of the variance? - correct answer ✔✔standard deviation
A confidence interval is centered around - correct answer ✔✔the sample mean Following statistical testing, which of these is the name for the range of values in which a population parameter is likely to occur, given some probability level? - correct answer ✔✔confidence interval A small effect size indicates that the - correct answer ✔✔independent variable has a small effect on the dependent variable The magnitude of the independent variable's influence on the dependent variable is called the _______. - correct answer ✔✔effect size A Cohen's d value of 0.85 can be interpreted as indicating a - correct answer ✔✔large effect Which of these is an assumption when using a nonparametric test? - correct answer ✔✔Nonparametric tests are assumption-free. Which measure of central tendency can be compared between different groups for nonparametric tests? - correct answer ✔✔mode Most statistical tests are - correct answer ✔✔parametric Parametric tests are appropriate if the dependent variable data being collected are measured at which scale level? - correct answer ✔✔interval or ratio Which of these is an assumption when using a parametric test? - correct answer ✔✔The variables are normally distributed in the population. If, upon testing a hypothesis, the null hypothesis is rejected, what happens? - correct answer ✔✔The alternative hypothesis is accepted.
Which of these is the hypothesis stating that there is not a meaningful difference between the groups or conditions under investigation? - correct answer ✔✔Null hypothesis Which factor should be considered in choosing a statistical test? - correct answer ✔✔The number of variables to be compared. A researcher is interested in examining whether students who distribute practice over a number of short study sessions differ in their test performance from students who mass practice over a single long session. Her prediction that students who distribute practice will perform better than students who mass practice is the - correct answer ✔✔Research hypothesis In an inferential statistical test, after rejecting the _____ hypothesis, you have found support for the _____ hypothesis. - correct answer ✔✔null, alternative A Type II error is also referred to as a __________. - correct answer ✔✔false negative A Type I error involves erroneously _______ the _______ hypothesis. - correct answer ✔✔rejecting, null Which type of error is typically less of a concern to researchers? - correct answer ✔✔a type II error Which symbol is used to indicate the probability of making a Type II error? - correct answer ✔✔β The probability of making a Type I error is called _______ and is typically set to 5% in research. - correct answer ✔✔alpha It is most desirable for a study to have - correct answer ✔✔high power Power is calculated as _____. - correct answer ✔✔ 1 － β
Correlation coefficient: - correct answer ✔✔A number ranging from +1.00 to -1. that describes the degree to which two variables are related. Descriptive statistics - correct answer ✔✔A range of procedures for depicting the main aspects of sample data, without necessarily inferring to a larger population. Descriptive statistics includes calculations such as the mean, median, mode, range, standard deviation, and correlation. Deviation score - correct answer ✔✔Indicates how far a single score in the sample deviates from the mean of the sample Direction - correct answer ✔✔The sign of a correlation coefficient (regardless of the number), which can be positive (+) or negative (-). dispersion - correct answer ✔✔Statistics that quantify the answer to the question, "How dissimilar (or similar) are the different scores to each other in a sample?" dispersion (spread) - correct answer ✔✔The degree to which a set of scores are different from each other, or from the mean of the data. effect size - correct answer ✔✔Indicates how large the independent variable's effect is on the dependent variable. Effect size can be thought of as the magnitude, or size, of the difference. floor effect - correct answer ✔✔A skewed distribution of data where the mode is close to the lower limit of the scale. This is in contrast to a ceiling effect, where the mode is close to the upper limit of the scale. hypothesis - correct answer ✔✔A prediction or proposed explanation for an observation or phenomenon. inferential statistics - correct answer ✔✔A range of statistical techniques that allow inferences about characteristics of a population to be drawn from a sample of data from that population. These techniques include approaches for testing hypotheses,
estimating the value of parameters, and selecting among a set of competing models. interval data (or interval level or scale) - correct answer ✔✔Measured along a scale in which there is equal spacing between the units of measurement. These data lack can be described with a mean but a meaningful zero point. Levels of data measurement (also known as scales of data measurement): - correct answer ✔✔Describe the degree of specificity with which a variable was measured. These levels include nominal, ordinal, interval, and ratio. mean - correct answer ✔✔Numerical average of a set of scores, computed as the sum of all scores divided by the number of scores. median - correct answer ✔✔The midpoint in a distribution; that is, the score or value that divides it into two equal-sized halves. The median is particularly useful when analyzing data that have outliers, as it is more resistant to the influence of extreme values than is the mean. mode - correct answer ✔✔The most frequently occurring score in a set of data. To determine the mode, simply tabulate the frequency of each value in the data set. The mode is the most frequent. multimodal - correct answer ✔✔A set of data, when graphed, that has more than two distinct peaks, or modes. negative correlation - correct answer ✔✔A relationship in which the variables move in opposite directions. This means that as one variable increases, the other decreases. Nominal data (or nominal data) (categorical) - correct answer ✔✔Measurement that fits into discrete, unordered categories. Nonparametric tests - correct answer ✔✔Statistical tests in which specific assumptions cannot be met.
Ratio level (or ratio data) - correct answer ✔✔Similar to interval, but include a true, meaningful zero point. These data have the highest level of precision compared to nominal, ordinal, and interval data. Relationship statistics - correct answer ✔✔Also referred to as multivariate statistics; characterize how two or more variables are related. standard deviation - correct answer ✔✔A measure of the variability of a set of scores, indicating how narrowly or broadly they deviate from the mean. Can be found by taking the square root of the variance. statistically signficant - correct answer ✔✔The outcome of a test to determine the likelihood that a sample is from a given population. If the conclusion is that the sample is not from the given population then the result is said to be statistically significant. statistical test - correct answer ✔✔An inferential test, which is a mathematical procedure, used to evaluate an empirical hypothesis by determining the likelihood of a sample resulting from a given population. strength - correct answer ✔✔The numerical value of a correlation coefficient (not the sign), which indicates how closely two variables are related to one another. The closer the value is to 1.00, the higher the strength. Type I error - correct answer ✔✔Rejecting the null hypothesis when it is true; also known as a false positive. Type II error - correct answer ✔✔Failing to reject the null hypothesis when it is false; also known as a false negative. variance - correct answer ✔✔A number that represents the mean squared deviation score.
