ap psych module 8 test
a researcher is conducting a study and wants to ensure that the sample chosen to participate will yield good results. 1) why is it better to have a large sample of data instead of a small sample? 2) what happens to reliability as sample size increases?
1) 2hy is it better to have a large sample of data instead of a small sample? it is better to have a large sample of data in order to include a variety of backgrounds and demographics, which may yield a larger variation in data. if the data were too closely related, the researcher would struggle to make insightful observations. we are able to have more confidence in our data, when the data reflects real differences in population. 2) what happens to reliability as sample size increases? when the difference between the sample size is large, it has statistical significance. the reliability increases as the sample size increases as the data will reflect real differences in population.
for which of the following distributions of scores would the median most clearly be a more appropriate measure of central tendency than the mean?
10, 22, 8, 9, 6
in a group of five individuals, two report annual incomes of $10,000, and the other three report incomes of $14,000, $15,000, and $31,000, respectively. the mode of this group's distribution of annual incomes is
10,000
during the last central high school basketball game, the starting five players scored 11, 7, 21, 14, and 7 points, respectively. for this distribution of scores, the range is
14
the iq scores of the five members of the duluth family are 100, 82, 104, 96, and 118. for this distribution of scores, the range is
36
on a 10-item test, three students in Professor Hsin's advanced chemistry seminar received scores of 2, 5, and 8, respectively. for this distribution of test scores, the standard deviation is equal to the square root of
6
for which of the following distributions of scores would the median most clearly be a more appropriate measure of central tendency than the mean?
6, 18. 4, 5, 2
if scores on the wechsler adult intelligence scale (WAIS) are normally distributed, with a mean of 100 and a standard deviation of 15, what percentage of scores will fall between 85 and 115?
68
what is the range of the following: 12, 25, 33, 40, 80?
68
in a normal distribution, what percentage of the scores in the distribution falls within one standard deviation on either side of the mean?
68 percent
during the past month, henri and sylvia each ate 10 candy bars, while jerry ate 8, tricia ate 6, and tahli ate only 1. the mean number of candy bars eaten by these individuals was
7
mr. and mrs. berry have five children aged 2, 3, 7, 9, and 9. the median age of the berry children is
7
mr. and mrs. klostreich have six children aged 5, 6, 6, 7, 8, and 16. the mean age of the klostreich children is
8
during the past year, zara and ivan each read 2 books, but george read 9, ali read 12, and marsha read 25. The median number of books read by these individuals was
9
coach thornton attended a clinic to improve her basketball coaching skills. afterward, she randomly assigned her seventh-grade players to two groups: group 1 will be coached by the new method and group 2 will be coached by the old method. she then measured their performance at one team practice to judge the effectiveness of the new coaching method. which of the following might affect the statistical significance of his study?
by testing only two groups, coach thornton 's sample size may be too small and unrepresentative.
a soft drink company recently invested in a new advertising campaign to increase sales. which of the following would allow executives to best judge the results of their latest commercials?
compare the means of sales before and after the beginning of the new campaign to determine statistical significance
to determine whether a research finding is statistically significant, researchers
compare the means of the control group and experimental group.
what are descriptive statistics?
descriptive statistics are used to measure and describe the characteristics of the group under study when researchers gather data.
the distributions of which of the following types of data are most likely to form a normal curve?
height
dr. devries is interested in measuring how practice in problem solving affects this ability. the population of interest is high school seniors, and the sample consists of students who attend an exclusive college preparatory school. half of the sample receives practice in solving particular types of problems, while the other half does not. both groups take the same problem-solving test. which of the following might best explain why dr. devries may not be able to generalize his findings?
his sample is not representative of the population.
which makes finding statistical significance more likely?
large sample size
why are researchers careful to use large, representative samples in their studies?
larger, representative sample sizes help ensure reliable and valid results.
in a distribution of test scores, which measure of central tendency would likely be the most affected by a couple of extremely high scores?
mean
the arithmetic average of a distribution of scores is the
mean
the most commonly reported measure of central tendency is the
mean
when mr. adams calculated his students' algebra test scores, he noticed that two students had extremely low scores. which measure of central tendency is affected most by the scores of these two students?
mean
which measure of central tendency is most influenced by outliers (data that is extremely different from other data in the set)?
mean
which measure of central tendency would a baseball manager be most likely to rely on in picking a pinch hitter in a tie game?
mean
which measure of central tendency would be most appropriate in determining housing values in a particular community?
median
the difference between the highest and lowest scores in a distribution is the
range
which measure of variation is most affected by extreme scores?
range
variation is to central tendency as ________ is to ________.
range; median
how do we know whether an observed difference can be generalized to other populations?
representative samples are better than biased samples. the best basis for generalizing is not from the exceptional and memorable cases one finds at the extremes but from a representative sample of cases. less-variable observations are more reliable than those that are more variable. an average is more reliable than an outlier. more cases are better than fewer because one will gather more data to compare it to so that the results of the experiment are accurate.
evelyn wants to know how consistent her bowling scores have been during the past season. which of the following measures would be most relevant to this specific concern?
standard deviation
which of the following is a measure of the degree of variation among a set of events?
standard deviation
what do researchers call a difference between the means of experimental and control groups when they know the averages are reliable and the difference between the groups is unlikely due to random chance or extraneous variables?
statistically significant
when the observed difference between the means of an experimental group and control group are not likely due to chance, researchers conclude that this difference is
statistically significant
why do we need statistics in Psychology and in everyday life?
statistics are the tools that allow them to measure variables and then interpret results. accurate statistical understanding benefits everyone. to be an educated person today is to be able to apply simple statistical principles to everyday reasoning. we don't need to memorize complicated formulas to think more clearly and critically about data. statistics can also show inaccuracy in the way they're presented.
professor teruya noticed that the distribution of students' scores on her last biology test had an extremely small standard deviation. this indicates that the
students' scores tended to be very similar to one another.
descriptive statistics ___________, while inferential statistics ______________.
summarize data; assess if data can be generalized
how do we describe data using the three measures of central tendency?
summarize the data using some measure of central tendency, a single score that represents a whole set of scores. you can describe these using mean, median, and mode. the mean is the average, the median is the middle number, and the mode is the number that appears the most often. but consider what happens to the mean when a distribution is lopsided, when it's skewed by a few way-out scores.
the range is
the difference between the highest and lowest scores in a distribution.
seven members of a Girl Scout troop report the following individual earnings from their sale of candy: $4, $1, $7, $6, $8, $2, and $7. in this distribution of individual earnings
the mean is less than the mode and less than the median.
seven members of a boys' club reported the following individual earnings from their sale of cookies: $2, $9, $8, $10, $4, $9, and $7. in this distribution of individual earning
the median is less than the mean and greater than the mode.
why would the median, rather than the mean, be the appropriate measure of central tendency in determining housing values in a particular community?
the median is minimally affected by extreme scores.
what is the relative usefulness of the two measures of variation?
the two measures of variation are useful when finding the amount of variation in data and measuring how much scores deviate from one another. these measures of variation can be seen in many real life scenarios, including studying demographics.
if a result is statistically significant, this means that the
there is less than a 5 percent likelihood that the results occurred by chance.
why are researchers so careful about drawing conclusions regarding statistical significance?
they want to make sure an observed difference isn't due to chance.
a researcher calculates statistical significance for her study and finds a 5 percent chance that results are due to chance. which of the following is an accurate interpretation of this finding?
this is the minimum result typically considered statistically significant.
what are inferential statistics?
we can use inferential statistics to determine how reliable and statistically significant differences are. this way we will know if results can be generalized to a larger population.
