Data Analysis & Inferential Testing

What is quantitative data?

Numerical data that can be measured and analyzed statistically

What is qualitative data?

Non-numerical data expressed in words, descriptions, meanings and experiences

What are quantitative data collection techniques?

Experiments, structured observations, closed questionnaires, standardized tests

What are qualitative data collection techniques?

Interviews, unstructured observations, open questionnaires, case studies

What is primary data?

Data collected directly by researcher for their specific study

What is secondary data?

Data collected by someone else for different purpose, used by current researcher

What is meta-analysis?

Statistical technique combining results from multiple studies on same topic

What is the mean?

Average score calculated by adding all scores and dividing by number of scores

What is the median?

Middle value when scores are arranged in ascending order

What is the mode?

Most frequently occurring score in a data set

How do you calculate the mean?

Add all values together, divide by number of values (Σx/n)

How do you calculate the median?

Arrange scores in order, find middle value (or average of two middle values)

How do you calculate the mode?

Count frequency of each value, identify most common

What is range?

Difference between highest and lowest scores (highest - lowest + 1)

What is standard deviation?

Measure of spread showing average distance of scores from the mean

How do you calculate range?

Highest score - lowest score + 1

How do you calculate percentages?

(Part/whole) × 100

What is a positive correlation?

As one variable increases, the other variable also increases

What is a negative correlation?

As one variable increases, the other variable decreases

What is zero correlation?

No relationship between the two variables

What are graphs used for?

Visual display of data patterns and relationships

What are tables used for?

Organized presentation of numerical data in rows and columns

What are scattergrams used for?

Showing correlation between two continuous variables

What are bar charts used for?

Comparing discrete categories or groups

What are histograms used for?

Showing frequency distribution of continuous data

What is normal distribution?

Bell-shaped curve where most scores cluster around mean

What are characteristics of normal distribution?

Symmetrical, mean = median = mode, 68% within 1 SD, 95% within 2 SDs

What is positive skew?

Most scores at lower end, tail extends toward higher scores

What is negative skew?

Most scores at higher end, tail extends toward lower scores

What is a correlation coefficient?

Number between -1 and +1 indicating strength and direction of correlation

How do you interpret correlation strength?

0.1-0.3 weak, 0.4-0.6 moderate, 0.7-0.9 strong, 1.0 perfect

What is nominal level of measurement?

Data in categories with no order (e.g., gender, eye color)

What is ordinal level of measurement?

Data in ranked categories with order but unequal intervals (e.g., rating scales)

What is interval level of measurement?

Data with equal intervals between values (e.g., test scores, reaction time)

What is coding in content analysis?

Categorizing qualitative data into quantifiable themes or categories

What is statistical testing?

Using mathematical procedures to determine if results are statistically significant

What is the sign test?

Non-parametric test comparing two conditions in repeated measures design

When do you use the sign test?

Nominal data, repeated measures design, looking for difference between conditions

How do you calculate the sign test?

Count positive/negative differences, use smaller value as calculated S

What is probability in statistics?

Likelihood that results occurred by chance (p-value)

What is statistical significance?

Results unlikely to have occurred by chance (usually p<0.05)

What are statistical tables used for?

Finding critical values to determine if results are significant

What are critical values?

Threshold values that calculated statistic must reach for significance

What is Type I error?

Rejecting null hypothesis when it's actually true (false positive)

What is Type II error?

Accepting null hypothesis when it's actually false (false negative)

When do you use Spearman's rho?

Correlation test for ordinal data or non-normal distributions

When do you use Pearson's r?

Correlation test for interval data with normal distribution

When do you use Wilcoxon test?

Difference test for ordinal data, repeated measures design

When do you use Mann-Whitney test?

Difference test for ordinal data, independent groups design

When do you use related t-test?

Difference test for interval data, repeated measures design

When do you use unrelated t-test?

Difference test for interval data, independent groups design

When do you use Chi-Squared test?

Association test for nominal data in categories

What factors affect choice of statistical test?

Level of measurement, experimental design (repeated/independent), type of hypothesis

Example of quantitative data in psychology

Reaction times in milliseconds, number of words recalled, IQ scores

Example of qualitative data in psychology

Interview responses about experiences, observational descriptions of behavior

Example of primary data collection

Researcher conducts own experiment measuring memory performance

Example of secondary data use

Using government statistics on mental health rates for research

Evaluation of quantitative data - strengths

Objective, reliable, allows statistical analysis, can establish cause and effect

Evaluation of quantitative data - weaknesses

May lack depth, doesn't capture meaning, reductionist approach

Evaluation of qualitative data - strengths

Rich detailed data, captures meaning and context, holistic approach

Evaluation of qualitative data - weaknesses

Subjective, difficult to analyze, low reliability, can't establish causation