What are the four ways of obtaining knowledge
Intuition; guts, emotions, and instinct
Authority; accept ideas from authority figures
Rationalism; using logic and reasoning
Empiricism; observation and experience
What is the difference between a bar graph and a histogram?
Bar graph: A representation of a frequency distribution, where vertical bars are centered above each category along the x-axis and are separated from each other by a space, indicating that the levels of the variable represent distinct, unrelated categories
Histogram:
A graphical representation of a frequency distribution, in which vertical bars centered above scores on the x-axis touch each other to indicate that the scores on the variable represent related, increasing values
Describe what a positive and negative skewed distribution looks like
Positively Skewed Distribution: Highest point of curve is towards the left
Negatively Skewed Distribution: Highest point of curve is towards the right
What is a Z score?
the number of standard deviations an individual score is from the mean
What is partial correlation?
A technique used to determine the effects of a third variable by removing the effect of the third variable from the correlation of the remaining two variables
Identify and compare descriptive methods
Naturalistic Observation; Observing humans or other animals in their natural habitat
Observational/Laboratory Method; Making observations of humans/animals behavior
Case Study Method; An in depth study of one or more individuals
Survey Method; Questioning individuals on a topic and then describing their responses
What is the difference between a qualitative and a quantitative variable?
Qualitative variable: A categorical variable for which each value represents a discrete category
Quantitaive variable: A variable for which the scores represent a change in quantity
What is the difference between Mesokurtic, Platykurtic, Leptokurtic?
Mesokurtic: Normal curves that have peaks of medium height and distributions that are moderate in breadth
Platykurtic: Normal curves that are short and more dispersed (broader)
Leptokurtic: Normal curves that are tall and thin, with only a few scores in the middle of the distribution having a high frequency.
Describe what a percentile rank is
A score that indicates the percentage of people who scored at or below a given raw score
Whats the difference between Pearson product-moment correlation coefficient (Pearson’s r), point-biserial correlation coefficient, phi coefficient and Spearman’s rank-order correlation coefficient?
Pearson product-moment correlation coefficient (Pearson’s r): The most commonly used correlation coefficient when both variables are measured on an interval or ratio scale
point-biserial correlation coefficient:The correlation coefficient used when one of the variables is measured on a constant nominal scale and the other is measured on an interval or ratio scale
phi coefficient: The correlation coefficient used when both measured variables are constant and nominal.
Spearman’s rank-order correlation coefficient: The correlation coefficient used when both of the variables are measured on an ordinal (ranking) scale
What makes science scientific?
Systematic Empiricism; an observation of relationships that is carefully structured, so you can learn about cause and effect relations between variables.
Empiricism is the process of making an observation about experiences.
Design project that answers a research question
Collect data (numbers or information)
Anaylze the data
Interpret the data (in relation to question)
Share the results
David Day has 8 red balls, 3 green balls, 6 yellow balls, 3 orange balls, 13 black balls and 15 blue balls in his bag.
Find the Mean, Median, Mode & Range
Mean = 8
Median = 7
Mode = 3
Range = 12
Find the interquartile range of the following data.
10 5 6 8 4 3 4
Q1: 4
Median: 5
Q3: 8
what are the unique properties of the normal curve?
Symmetrical, bell-shaped frequency polygon, normal distribution mean = median = mode
What are the assumptions of correlational analysis?
Correlation focuses on linear relationships only
Correlation do not work well if the data range is "restricted"
Variability should be consistent at all values of x
Data are continuous
Name & Define All Of The Scales of Measurement
Nominal scale
A scale in which objects or individuals are broken into categories that have no numerical properties; Name-type data
Categorical data; ethnicity, gender, political affiliation
Interval scale
A scale in which the units of measurement (intervals) between the numbers on the scale are all equal in size
Number based with interpretable and consistent distance between values
For example, the Fahrenheit temperature scale is an interval scale of measurement
Ordinal scale
A scale in which objects or individuals are categorized and the categories form a rank order along a continuum; Rankings
Ordinal data are often referred to as ranked data because the data are ordered from highest to lowest, or biggest to smallest. For example, reporting how students did on an exam based simply on their rank (highest score, second highest, and so on) would be an ordinal scale
Ratio scale
A scale in which, in addition to order and equal units of measurement, there is an absolute zero that indicates an absence of the variable being measured
Like interval, but zero has a true meaning
Examples of ratio scales of measurement include weight, time, and height
What is a frequency polygon?
A line graph of the frequencies of individual scores
Differentiate between measures of variation
Range: A measure of variation; the difference between the lowest and the highest scores in a distribution
Interquartile range: the spread of the central 50% of a sample (used with a median) further breaks down bottom half and top half; value between median and lowest and median and highest
Standard deviation: A measure of how spread out numbers are in a set of values; average difference between the scores and mean of the distribution
What is standardization?
The process of putting different variables on the same scale to compare them. to standardize variables, you calculate the mean and standard deviation
Describe the difference between strong, moderate, and weak correlation coefficients.
Strong: + .70 - 1.00
Moderate: + .30 - .69
Weak: + 00 - .29
Explain the four properties of measurement and how they are related to the four scales of measurement
Identify; Objects that are different receive different scores
E.g, If participants in a study had different political affiliations, they would receive different scores
Magnitude (ordinality; When the ordering of the numbers reflects the ordering of the variables; numbers are assigned in order so that some numbers represent more or less of the variable being measured than others
Equal Unit Size ; When a difference of 1 is the same amount throughout the entire scale
E.g, The difference between people who are 64 inches tall and 65 inches tall is the same as the difference between people who are 72 inches tall and 73 inches tall
Absolute Zero; A property of measurement in which assigning a score of 0 indicates an absence of the variable being measured
E.g, Time spent studying would have the property of absolute zero because a score of 0 on this measure would mean an individual spent no time studying. However, a score of 0 is not always equal to the property of absolute zero
How can you identify a misleading graph?
Dates out of order
No y axis
Missing axis labels
Make sure y axis starts at 0
How do you compute the range of a central percentage
x̄ ± s represents the central 65% of people’s scores on something
x̄ ± 2(s) represents the central 95% of people’s scores on something
x̄ ± 3(s) represents the central 99% of people’s scores on something
A patient recently diagnosed with Alzheimer’s disease takes a cognitive abilities test and scores a 45. The mean on this test is 52 and the standard deviation is 5. What is the patient’s percentile rank?
8.1%
Compute and interpret the correlation
X Y
2 9
1 10
3 6
0 8
4 2
- 0.80