Physiology lab quiz 1

Independent variable

The variable the researcher intentionally changes or manipulates.

Independent variable example

In “Does exercise increase heart rate?”, exercise is the independent variable.

Dependent variable

The response or outcome being measured.

Dependent variable example

In “Does exercise increase heart rate?”, heart rate is the dependent variable.

Observed variable

A variable the researcher studies but cannot manipulate.

Examples of observed variables

Sex, blood type, and shirt size.

Comparator

What the experimental result is compared against.

Examples of comparators

Control group, control condition, baseline measurement, or another group/reference point.

Two main categories of study designs

Descriptive and experimental.

Descriptive study

A study with no intervention or manipulation; there is no independent variable.

Experimental study

A study in which the researcher introduces an intervention or manipulation.

Types of descriptive studies

Case study, cross

Case study

Study of 1–2 instances of an observed phenomenon.

Cross

sectional study

Cross

sectional example

Longitudinal study

A group of subjects is followed over time to see how a variable changes.

Longitudinal example

Measuring children's height every year.

Retrospective study

Looks for a relationship between a current condition and something that occurred in the past.

Types of experimental studies

Randomized controlled, pre/post, time series, and crossover.

Randomized controlled study

Subjects are split and randomly assigned to either an experimental group or a control group.

Pre/post study

The dependent variable is measured before a manipulation and once after the manipulation.

Time series study

The dependent variable is measured before a manipulation and then multiple times afterward.

Crossover study

Subjects are divided into groups; every group receives all treatments, but in different orders.

Washout period

A period between treatment conditions used in a crossover study.

Key feature of crossover design

Every subject receives all treatments, but the treatments may occur in different orders.

Null hypothesis

The results being compared are not different.

Statistically significant

The results are unlikely to be the same under the null hypothesis.

When do you reject the null hypothesis?

When p < 0.05, using an alpha level of 0.05.

When do you fail to reject the null hypothesis?

When p ≥ 0.05, using an alpha level of 0.05.

Easy p

value rule

Chi

square test

Dependent t

test

Independent t

test

One

way ANOVA

Repeated measures ANOVA

Used to compare more than 2 means from the same people/subjects.

2 means + same people

Dependent t

2 means + different people

Independent t

More than 2 means + different people

One

More than 2 means + same people

Repeated measures ANOVA.

Observed vs expected frequencies

Chi

X

axis

Y

axis

Bar graph

Used for categorical variables and for pre/post designs.

Line graph

Used when the independent variable is continuous.

Examples of continuous independent variables

Weight, temperature, and time.

Scatterplot

Shows the relationship between two variables.

Scatterplot example

Hours studied versus exam performance.

Raw data table

A table used to record individual subject data.

Raw data table organization

Subject number, independent variable, then dependent variable(s).

Summary table

A table used to summarize experimental results.