Chapter 3: Research Methods: Statistics

descriptive stats

describe a set of data

variance

how much an variable differs from the expected value

range

spread between the highest # and lowest #

mean

the average

reliability

the study can be replicated and produce the same or similar variable

false consensus effect

a bias where people tend to overestimate the extent to which their opinions, beliefs, preferences, values, and habits are normal and typical of those of other

reliability tests

a test can be reliable but invalid, but a test cannot be valid unless it is reliable, summary: a test must always be reliable

inferential stats

determine whether or not findings can be applied to the larger population from which the sample was selected

random assignment

divide certain participants into groups

validity

does the study measure what the researcher intended to measure?

group matching

ensure that the control/experimental groups are equivalent on specific criteria

Pvalue

estimate of the probability that a result is caused by chance

z-score

number of deviations from the mean or score of zero

stratified random sampling

population is divided into two or more groups (strata) based on the population, subsamples like age, grade, and income can be randomly selected from each state

scatterplots

positive > up, rising = / negative > down, falling = \ no correlation

measures of variability

range, variance, standard deviation

inferential stats must be a.....

representative of the population you wish to study

replication

research cannot be replicated without decent operationally defining variables,

internal validity

results of the experiment can be attributed to the manipulation of the independent variable rather than a confounding variable

random sampling

select people from a population, it allows you to generalize your results

standard deviation

square root of the variance, how much it deviates from the mean

what is needed to understand a number set?

statistics

hypothesis testing: type I error

thinking the results are correct, but they are not = overconfidence

true or false: a strong correlation is not enough to establish a cause and effect relationship

true

what are the percentages for standard deviation?

1 SD = 68% 2 SD = 95% 3 SD = 99%

The four zebras at the Turtle Back Zoo in West Orange, NJ are 7, 1, 9, and 14. What is the average age of the zebras at the zoo? What is the variance?

average age = 7.75 variance = 21.7

what are visual representations of frequency distributions?

barographs and histograms

hypothesis testing: type II error

being right, but think you are wrong = too nervous

correlation coefficient

between -1 and +1

external validity

extend to which findings of a study can be generalized to other contexts, generalize the population

what are the 2 types of validity

internal and external

what are inferential stats used to observe?

look at differences between experimental and control groups, sample size, and determine how those differ

From a sample, these are the ages of women who had side effects from a drug given to them: 22, 25, 42, 30, 35, 30, 39, 40, 44, 34, 38, 33, 28, 38, 29, 42, 42, and 40, what is the mean, median, and mode?

mean = 38 median = 39.24 mode = 42

Patrick has seven dogs, their ages are 11, 4, 5, 2, 6, 7, and 2, what is the mean, median, and mode?

mean = 4 median = 5 mode = 2

Emily scores a 96, 90, 100, 100, 86, 88, and 98 on her Italian quizzes, what is the mean, median, and mode?

mean = 94 median = 96 mode = 100

statistical significance

measure of the likelihood due to chance

best measure of central tendency

median

measures of central tendency

mode, mean, median

mode

most common number