EDPSY 101: Research Methods & Statistical Analysis - Class #5

These flashcards cover key concepts from the lecture on Central Tendency and Variability, including definitions and principles important for understanding statistical analysis.

What is the purpose of statistical modeling?

Statistical modeling aims at predicting processes in the real world and must fit the observed data as accurately as possible.

What are the four moments in a probability distribution?

First Moment: Mean; Second Moment: Variance; Third Moment: Skewness; Fourth Moment: Kurtosis.

What does a positively skewed distribution indicate?

A positively skewed distribution has scores bunched at low values with the tail pointing to high values.

What is kurtosis in statistics?

Kurtosis refers to the 'heaviness' of the tails of a distribution, with types such as leptokurtic (heavy tails) and platykurtic (light tails).

What defines the mode in a dataset?

The mode is the most frequent score in a dataset.

How do you find the median?

The median is the middle score when the data are ordered; if there is an even number of scores, it is the average of the two middle values.

What is the mean?

The mean is the sum of scores divided by the number of scores.

What is the range in a dataset?

The range is the smallest score subtracted from the largest score.

What is the formula for calculating the variance?

Variance measures the average squared deviations from the mean; it shows how spread out the scores are.

What is a standard deviation?

Standard deviation is the square root of the variance and gives a measure of dispersion in the same units as the data.

What are Z-scores used for in statistics?

Z-scores standardize a score with respect to other scores in the group, expressing how many standard deviations a score is away from the mean.

What percentage of z-scores lie between -1.96 and 1.96?

Approximately 95% of z-scores lie between -1.96 and 1.96.

What is the importance of checking validity and reliability of instruments in research?

Checking validity and reliability helps to gain confidence in the measurement process and findings.

What are the two main types of research discussed?

The two main types of research are correlational (descriptive) and experimental.

What does 'sampling error' refer to?

Sampling error refers to the error caused by observing a sample instead of the whole population.